Case Letter

To the Editor:

Uveitis associated with tattoos is common, yet the etiology and optimal treatment options for this phenomenon remain unclear. Possible causes include a delayed hypersensitivity reaction to tattoo ink antigen or systemic sarcoidosis localized to the skin.¹ Long-term treatment options include topical, intralesional, and systemic corticosteroids or immunosuppressants.² Short-term options often include direct surgical excision and laser treatment. However, laser removal of tattoo pigment typically involves multiple sessions over the course of years, and there is a risk for antigen dispersal that may lead to anaphylaxis. Determining the most effective and safe treatment for a patient with progressive and severe ocular symptoms can be challenging. We describe a patient with cutaneous blue ink tattoos who developed chronic bilateral glaucoma, iritis, uveitis, and ocular hypertension that was refractory to multiple systemic medications and ophthalmologic procedures but responded to CO₂ laser ablation.

A 27-year-old man with an active smoking history presented to our laser surgery center with a rash of approximately 4 years’ duration in areas with blue tattoo ink on both forearms. He was referred by his ophthalmologist due to bilateral uveitis and iritis and subsequent ocular hypertension and glaucoma that developed approximately 5 years after tattoo placement on the bilateral forearms. When the rash first appeared, the skin in the areas of the blue tattoo ink had hyperpigmented pruritic plaques. The patient was treated by a dermatologist with topical steroids to help reduce the itching and inflammation. Around the same time, he also started having ocular symptoms—vitreous floaters, erythema, eye pain, and blurriness—and was diagnosed with iritis of unclear etiology by ophthalmology. Figure 1 documents the patient’s clinical course. Due to escalating intraocular pressure and symptoms, he was referred to a glaucoma specialist and a rheumatologist. Systemic and rheumatologic medical conditions were ruled out with negative results on a series of blood tests (eg, rheumatoid factor, HLA-B27, antinuclear antibody, lysozyme, interferon gamma release assay, erythrocyte sedimentation rate, C-reactive protein, hepatitis B/C virus, Treponema pallidum, HIV), and magnetic resonance imaging of the brain was negative, ruling out demyelinating disease. Laboratory workup for sarcoidosis also was performed. The angiotensin-converting enzyme level was 30 U/L (reference range, 9-67 U/L), and a chest radiograph and computed tomography with contrast indicated no evidence of cardiopulmonary involvement. Although sarcoidosis could not be definitively ruled out, no other cause could be determined, and the patient’s glaucoma specialist diagnosed him with tattoo-associated uveitis. The patient was started on brimonidine, latanoprost, prednisolone, and dorzolamidetimolol eye drops, as well as acetazolamide (500 mg twice daily) and oral prednisone (various doses). Over the next 3 years, the patient continued to have symptoms, and immunosuppressant medications—methotrexate 20-25 mg weekly and adalimumab 40 mg every 2 weeks—were added to his treatment regimen. The patient also underwent bilateral ophthalmologic procedures, including a Baerveldt glaucoma implant procedure in the left eye and circumferential trabeculectomy in the right eye.

Despite these medications and procedures, the patient’s symptoms and intraocular pressure had not improved. At the current visit, punch biopsy of the tattooed skin and histologic examination showed dermal lymphoplasmacytic inflammation with scattered foreign-body giant cells associated with blue tattoo ink and overlying hyperkeratosis and spongiosis, consistent with allergic contact dermatitis (Figure 2). Because both immunosuppressant medications and ophthalmologic procedures had failed to control the progression of the ocular symptoms and the patient was at risk for permanent blindness, surgical excision and laser tattoo removal were considered as potential treatment options. Due to the large surface area and circumferential nature of the tattoos, there was a notable risk for disfiguring scars at both recipient and donor sites with surgical excision followed by graft placement. Thus, CO₂ laser ablation was the preferred treatment option. However, this procedure was not without risk for anaphylaxis if the tattoo pigment were to be released into systemic circulation. Thus, at the first visit, ablation was performed on 3 test spots and the patient was prescribed cetirizine, diphenhydramine, and prophylactic prednisone for a few days. The patient then received a total of 5 fully ablative CO₂ laser sessions (pulse energy: 200 mJ [15 J/cm²]; computerized pattern generator: 2-8-9 [85.2 J/cm²]; rate: 200 Hz [20 W], 3 passes) over 13 months to remove all visible blue ink in stages (Figure 3). Even with a shortened time course (as more time between laser sessions typically is preferred), the treatments were well tolerated with only mild hypertrophic scarring that responded to intralesional steroids (triamcinolone 10 mg/mL). On repeat skin biopsy during the treatment course, the superficial dermis demonstrated mostly scar tissue and near-total pigment removal—a 90% to 95% reduction in blue ink from prior biopsy—and minimal inflammation (Figure 4). Scant fine to coarse pigment deposition was seen in the deep dermis next to subcutaneous fat, which was unchanged from the previous biopsy. The patient’s ophthalmologic symptoms were tracked via improvement in intraocular pressure and stabilization of his vision, indicating rapid and complete resolution of the glaucoma after the last laser treatment. With resolution of his ocular symptoms, the patient was tapered off all immunosuppressant medications. The patient was lost to follow-up approximately 2 years after the final laser treatment.

Tattoo-associated uveitis initially was described in 1969 in 3 patients with light blue tattoos who developed tattoo granulomas and simultaneous uveitis. These cases were successfully treated with excision.³ Multiple cases have been reported since, often with bilateral uveitis and tattoos demonstrating noncaseating granulomatous inflammation that were treated with steroids.⁴ In 2018, a diagnosis of exclusion was proposed for uveitis associated with granulomatous tattoo reaction without sarcoidosis: tattoo granulomas with uveitis (TAGU).¹

In this case, sarcoidosis initially was high on the differential diagnosis. Sarcoidosis is an immune-mediated systemic disease of unknown etiology characterized by the presence of widespread noncaseating epithelioid cell granulomas, primarily seen in the pulmonary and lymphatic systems. However, it often initially manifests with cutaneous involvement with noncaseating “naked” granulomas in the dermis and subcutaneous tissue. Although TAGU cases have demonstrated noncaseating granulomas in association with dermal tattoo pigment on histopathology,^1,4 dermal lymphoplasmacytic inflammation with scattered foreign body giant cells was noted in our patient, which was more consistent with allergic contact dermatitis. Thus, it is important to consider that TAGU can be seen with varying histologic patterns. In patients with tattoos, sarcoidosis can manifest grossly as a papulonodular cutaneous reaction.⁵ Active smoking is associated with a decreased risk for sarcoidosis, and those who smoke are statistically more likely to have tattoos than the general population,^6,7 so our patient’s smoking history may be relevant. However, sarcoidosis was an unlikely diagnosis due to the serum angiotensin-converting enzyme level; results of a chest radiograph (bilateral adenopathy and coarse reticular opacities) and computed tomography (hilar and mediastinal adenopathy); and nonsarcoidal histopathology.

An allergic reaction to tattoo ink is caused by a delayed-type hypersensitivity reaction to a pigment hapten that can develop abruptly months to years after tattoo placement—1 year after tattoo placement in our patient. This reaction was seen in our patient’s blue pigment tattoos, although it is more commonly seen in red pigment tattoos.⁸ Although the etiology of TAGU is poorly understood, it also is hypothesized to be a delayed-type hypersensitivity response to tattoo ink particles, suggested by the pattern of lymphocytes infiltrating the tattoo and atypical T-cell infiltrate on vitreous biopsy.^9,10 Further research is required to elucidate the relationship between tattoos and uveitis.

Q-switched lasers (eg, 532-nm or 1064-nm Nd:YAG, alexandrite, or ruby lasers) are the standard treatment options for uncomplicated tattoo removal and employ a high-intensity, ultrashort pulse duration.¹¹ However Q-switched lasers require multiple sessions and target pigment-containing cells, releasing the tattoo particles into systemic circulation, which can potentially induce a severe allergic response.¹² In contrast, CO₂ lasers use a different mechanism, emitting energy at a wavelength of 10,600 nm, which is absorbed by intracellular water and allows for the ablation of the superficial epidermis along with the embedded ink with subsequent re-epithelialization, as well as heat-mediated thermal injury to allow for dermal collagen remodeling.¹³ In a 2021 retrospective study of ablative laser therapy for allergic tattoo reactions, patients were treated with the 10,600-nm ablative CO₂ laser and noted improvements in itching and burning with minimal adverse events.¹² Although using a CO₂ laser may not be considered a firstline treatment option for TAGU, the refractory clinical course and notable morbidity of surgical excision necessitated the use of ablative laser in our case.

Tattoo granulomas with uveitis is a rare diagnosis with the potential for serious permanent sequelae including blindness. Existing treatments such as topical and oral corticosteroids, immunosuppressants, surgical excision, and Q-switched lasers all are possible options, but in a patient with progressive ocular symptoms with other potential rheumatologic conditions and sarcoidosis ruled out, fully ablative CO₂ laser may be an effective treatment option. Our case demonstrated the successful treatment of TAGU with CO₂ laser ablation. Given the unclear etiology of TAGU and the limited evidence on treatment options and efficacy, our case contributes to the body of literature that can inform clinical management of this unusual and serious reaction.

To the Editor:

Uveitis associated with tattoos is common, yet the etiology and optimal treatment options for this phenomenon remain unclear. Possible causes include a delayed hypersensitivity reaction to tattoo ink antigen or systemic sarcoidosis localized to the skin.¹ Long-term treatment options include topical, intralesional, and systemic corticosteroids or immunosuppressants.² Short-term options often include direct surgical excision and laser treatment. However, laser removal of tattoo pigment typically involves multiple sessions over the course of years, and there is a risk for antigen dispersal that may lead to anaphylaxis. Determining the most effective and safe treatment for a patient with progressive and severe ocular symptoms can be challenging. We describe a patient with cutaneous blue ink tattoos who developed chronic bilateral glaucoma, iritis, uveitis, and ocular hypertension that was refractory to multiple systemic medications and ophthalmologic procedures but responded to CO₂ laser ablation.

A 27-year-old man with an active smoking history presented to our laser surgery center with a rash of approximately 4 years’ duration in areas with blue tattoo ink on both forearms. He was referred by his ophthalmologist due to bilateral uveitis and iritis and subsequent ocular hypertension and glaucoma that developed approximately 5 years after tattoo placement on the bilateral forearms. When the rash first appeared, the skin in the areas of the blue tattoo ink had hyperpigmented pruritic plaques. The patient was treated by a dermatologist with topical steroids to help reduce the itching and inflammation. Around the same time, he also started having ocular symptoms—vitreous floaters, erythema, eye pain, and blurriness—and was diagnosed with iritis of unclear etiology by ophthalmology. Figure 1 documents the patient’s clinical course. Due to escalating intraocular pressure and symptoms, he was referred to a glaucoma specialist and a rheumatologist. Systemic and rheumatologic medical conditions were ruled out with negative results on a series of blood tests (eg, rheumatoid factor, HLA-B27, antinuclear antibody, lysozyme, interferon gamma release assay, erythrocyte sedimentation rate, C-reactive protein, hepatitis B/C virus, Treponema pallidum, HIV), and magnetic resonance imaging of the brain was negative, ruling out demyelinating disease. Laboratory workup for sarcoidosis also was performed. The angiotensin-converting enzyme level was 30 U/L (reference range, 9-67 U/L), and a chest radiograph and computed tomography with contrast indicated no evidence of cardiopulmonary involvement. Although sarcoidosis could not be definitively ruled out, no other cause could be determined, and the patient’s glaucoma specialist diagnosed him with tattoo-associated uveitis. The patient was started on brimonidine, latanoprost, prednisolone, and dorzolamidetimolol eye drops, as well as acetazolamide (500 mg twice daily) and oral prednisone (various doses). Over the next 3 years, the patient continued to have symptoms, and immunosuppressant medications—methotrexate 20-25 mg weekly and adalimumab 40 mg every 2 weeks—were added to his treatment regimen. The patient also underwent bilateral ophthalmologic procedures, including a Baerveldt glaucoma implant procedure in the left eye and circumferential trabeculectomy in the right eye.

Despite these medications and procedures, the patient’s symptoms and intraocular pressure had not improved. At the current visit, punch biopsy of the tattooed skin and histologic examination showed dermal lymphoplasmacytic inflammation with scattered foreign-body giant cells associated with blue tattoo ink and overlying hyperkeratosis and spongiosis, consistent with allergic contact dermatitis (Figure 2). Because both immunosuppressant medications and ophthalmologic procedures had failed to control the progression of the ocular symptoms and the patient was at risk for permanent blindness, surgical excision and laser tattoo removal were considered as potential treatment options. Due to the large surface area and circumferential nature of the tattoos, there was a notable risk for disfiguring scars at both recipient and donor sites with surgical excision followed by graft placement. Thus, CO₂ laser ablation was the preferred treatment option. However, this procedure was not without risk for anaphylaxis if the tattoo pigment were to be released into systemic circulation. Thus, at the first visit, ablation was performed on 3 test spots and the patient was prescribed cetirizine, diphenhydramine, and prophylactic prednisone for a few days. The patient then received a total of 5 fully ablative CO₂ laser sessions (pulse energy: 200 mJ [15 J/cm²]; computerized pattern generator: 2-8-9 [85.2 J/cm²]; rate: 200 Hz [20 W], 3 passes) over 13 months to remove all visible blue ink in stages (Figure 3). Even with a shortened time course (as more time between laser sessions typically is preferred), the treatments were well tolerated with only mild hypertrophic scarring that responded to intralesional steroids (triamcinolone 10 mg/mL). On repeat skin biopsy during the treatment course, the superficial dermis demonstrated mostly scar tissue and near-total pigment removal—a 90% to 95% reduction in blue ink from prior biopsy—and minimal inflammation (Figure 4). Scant fine to coarse pigment deposition was seen in the deep dermis next to subcutaneous fat, which was unchanged from the previous biopsy. The patient’s ophthalmologic symptoms were tracked via improvement in intraocular pressure and stabilization of his vision, indicating rapid and complete resolution of the glaucoma after the last laser treatment. With resolution of his ocular symptoms, the patient was tapered off all immunosuppressant medications. The patient was lost to follow-up approximately 2 years after the final laser treatment.

Tattoo-associated uveitis initially was described in 1969 in 3 patients with light blue tattoos who developed tattoo granulomas and simultaneous uveitis. These cases were successfully treated with excision.³ Multiple cases have been reported since, often with bilateral uveitis and tattoos demonstrating noncaseating granulomatous inflammation that were treated with steroids.⁴ In 2018, a diagnosis of exclusion was proposed for uveitis associated with granulomatous tattoo reaction without sarcoidosis: tattoo granulomas with uveitis (TAGU).¹

In this case, sarcoidosis initially was high on the differential diagnosis. Sarcoidosis is an immune-mediated systemic disease of unknown etiology characterized by the presence of widespread noncaseating epithelioid cell granulomas, primarily seen in the pulmonary and lymphatic systems. However, it often initially manifests with cutaneous involvement with noncaseating “naked” granulomas in the dermis and subcutaneous tissue. Although TAGU cases have demonstrated noncaseating granulomas in association with dermal tattoo pigment on histopathology,^1,4 dermal lymphoplasmacytic inflammation with scattered foreign body giant cells was noted in our patient, which was more consistent with allergic contact dermatitis. Thus, it is important to consider that TAGU can be seen with varying histologic patterns. In patients with tattoos, sarcoidosis can manifest grossly as a papulonodular cutaneous reaction.⁵ Active smoking is associated with a decreased risk for sarcoidosis, and those who smoke are statistically more likely to have tattoos than the general population,^6,7 so our patient’s smoking history may be relevant. However, sarcoidosis was an unlikely diagnosis due to the serum angiotensin-converting enzyme level; results of a chest radiograph (bilateral adenopathy and coarse reticular opacities) and computed tomography (hilar and mediastinal adenopathy); and nonsarcoidal histopathology.

An allergic reaction to tattoo ink is caused by a delayed-type hypersensitivity reaction to a pigment hapten that can develop abruptly months to years after tattoo placement—1 year after tattoo placement in our patient. This reaction was seen in our patient’s blue pigment tattoos, although it is more commonly seen in red pigment tattoos.⁸ Although the etiology of TAGU is poorly understood, it also is hypothesized to be a delayed-type hypersensitivity response to tattoo ink particles, suggested by the pattern of lymphocytes infiltrating the tattoo and atypical T-cell infiltrate on vitreous biopsy.^9,10 Further research is required to elucidate the relationship between tattoos and uveitis.

Q-switched lasers (eg, 532-nm or 1064-nm Nd:YAG, alexandrite, or ruby lasers) are the standard treatment options for uncomplicated tattoo removal and employ a high-intensity, ultrashort pulse duration.¹¹ However Q-switched lasers require multiple sessions and target pigment-containing cells, releasing the tattoo particles into systemic circulation, which can potentially induce a severe allergic response.¹² In contrast, CO₂ lasers use a different mechanism, emitting energy at a wavelength of 10,600 nm, which is absorbed by intracellular water and allows for the ablation of the superficial epidermis along with the embedded ink with subsequent re-epithelialization, as well as heat-mediated thermal injury to allow for dermal collagen remodeling.¹³ In a 2021 retrospective study of ablative laser therapy for allergic tattoo reactions, patients were treated with the 10,600-nm ablative CO₂ laser and noted improvements in itching and burning with minimal adverse events.¹² Although using a CO₂ laser may not be considered a firstline treatment option for TAGU, the refractory clinical course and notable morbidity of surgical excision necessitated the use of ablative laser in our case.

Tattoo granulomas with uveitis is a rare diagnosis with the potential for serious permanent sequelae including blindness. Existing treatments such as topical and oral corticosteroids, immunosuppressants, surgical excision, and Q-switched lasers all are possible options, but in a patient with progressive ocular symptoms with other potential rheumatologic conditions and sarcoidosis ruled out, fully ablative CO₂ laser may be an effective treatment option. Our case demonstrated the successful treatment of TAGU with CO₂ laser ablation. Given the unclear etiology of TAGU and the limited evidence on treatment options and efficacy, our case contributes to the body of literature that can inform clinical management of this unusual and serious reaction.

To the Editor:

Uveitis associated with tattoos is common, yet the etiology and optimal treatment options for this phenomenon remain unclear. Possible causes include a delayed hypersensitivity reaction to tattoo ink antigen or systemic sarcoidosis localized to the skin.¹ Long-term treatment options include topical, intralesional, and systemic corticosteroids or immunosuppressants.² Short-term options often include direct surgical excision and laser treatment. However, laser removal of tattoo pigment typically involves multiple sessions over the course of years, and there is a risk for antigen dispersal that may lead to anaphylaxis. Determining the most effective and safe treatment for a patient with progressive and severe ocular symptoms can be challenging. We describe a patient with cutaneous blue ink tattoos who developed chronic bilateral glaucoma, iritis, uveitis, and ocular hypertension that was refractory to multiple systemic medications and ophthalmologic procedures but responded to CO₂ laser ablation.

A 27-year-old man with an active smoking history presented to our laser surgery center with a rash of approximately 4 years’ duration in areas with blue tattoo ink on both forearms. He was referred by his ophthalmologist due to bilateral uveitis and iritis and subsequent ocular hypertension and glaucoma that developed approximately 5 years after tattoo placement on the bilateral forearms. When the rash first appeared, the skin in the areas of the blue tattoo ink had hyperpigmented pruritic plaques. The patient was treated by a dermatologist with topical steroids to help reduce the itching and inflammation. Around the same time, he also started having ocular symptoms—vitreous floaters, erythema, eye pain, and blurriness—and was diagnosed with iritis of unclear etiology by ophthalmology. Figure 1 documents the patient’s clinical course. Due to escalating intraocular pressure and symptoms, he was referred to a glaucoma specialist and a rheumatologist. Systemic and rheumatologic medical conditions were ruled out with negative results on a series of blood tests (eg, rheumatoid factor, HLA-B27, antinuclear antibody, lysozyme, interferon gamma release assay, erythrocyte sedimentation rate, C-reactive protein, hepatitis B/C virus, Treponema pallidum, HIV), and magnetic resonance imaging of the brain was negative, ruling out demyelinating disease. Laboratory workup for sarcoidosis also was performed. The angiotensin-converting enzyme level was 30 U/L (reference range, 9-67 U/L), and a chest radiograph and computed tomography with contrast indicated no evidence of cardiopulmonary involvement. Although sarcoidosis could not be definitively ruled out, no other cause could be determined, and the patient’s glaucoma specialist diagnosed him with tattoo-associated uveitis. The patient was started on brimonidine, latanoprost, prednisolone, and dorzolamidetimolol eye drops, as well as acetazolamide (500 mg twice daily) and oral prednisone (various doses). Over the next 3 years, the patient continued to have symptoms, and immunosuppressant medications—methotrexate 20-25 mg weekly and adalimumab 40 mg every 2 weeks—were added to his treatment regimen. The patient also underwent bilateral ophthalmologic procedures, including a Baerveldt glaucoma implant procedure in the left eye and circumferential trabeculectomy in the right eye.

Despite these medications and procedures, the patient’s symptoms and intraocular pressure had not improved. At the current visit, punch biopsy of the tattooed skin and histologic examination showed dermal lymphoplasmacytic inflammation with scattered foreign-body giant cells associated with blue tattoo ink and overlying hyperkeratosis and spongiosis, consistent with allergic contact dermatitis (Figure 2). Because both immunosuppressant medications and ophthalmologic procedures had failed to control the progression of the ocular symptoms and the patient was at risk for permanent blindness, surgical excision and laser tattoo removal were considered as potential treatment options. Due to the large surface area and circumferential nature of the tattoos, there was a notable risk for disfiguring scars at both recipient and donor sites with surgical excision followed by graft placement. Thus, CO₂ laser ablation was the preferred treatment option. However, this procedure was not without risk for anaphylaxis if the tattoo pigment were to be released into systemic circulation. Thus, at the first visit, ablation was performed on 3 test spots and the patient was prescribed cetirizine, diphenhydramine, and prophylactic prednisone for a few days. The patient then received a total of 5 fully ablative CO₂ laser sessions (pulse energy: 200 mJ [15 J/cm²]; computerized pattern generator: 2-8-9 [85.2 J/cm²]; rate: 200 Hz [20 W], 3 passes) over 13 months to remove all visible blue ink in stages (Figure 3). Even with a shortened time course (as more time between laser sessions typically is preferred), the treatments were well tolerated with only mild hypertrophic scarring that responded to intralesional steroids (triamcinolone 10 mg/mL). On repeat skin biopsy during the treatment course, the superficial dermis demonstrated mostly scar tissue and near-total pigment removal—a 90% to 95% reduction in blue ink from prior biopsy—and minimal inflammation (Figure 4). Scant fine to coarse pigment deposition was seen in the deep dermis next to subcutaneous fat, which was unchanged from the previous biopsy. The patient’s ophthalmologic symptoms were tracked via improvement in intraocular pressure and stabilization of his vision, indicating rapid and complete resolution of the glaucoma after the last laser treatment. With resolution of his ocular symptoms, the patient was tapered off all immunosuppressant medications. The patient was lost to follow-up approximately 2 years after the final laser treatment.

Tattoo-associated uveitis initially was described in 1969 in 3 patients with light blue tattoos who developed tattoo granulomas and simultaneous uveitis. These cases were successfully treated with excision.³ Multiple cases have been reported since, often with bilateral uveitis and tattoos demonstrating noncaseating granulomatous inflammation that were treated with steroids.⁴ In 2018, a diagnosis of exclusion was proposed for uveitis associated with granulomatous tattoo reaction without sarcoidosis: tattoo granulomas with uveitis (TAGU).¹

In this case, sarcoidosis initially was high on the differential diagnosis. Sarcoidosis is an immune-mediated systemic disease of unknown etiology characterized by the presence of widespread noncaseating epithelioid cell granulomas, primarily seen in the pulmonary and lymphatic systems. However, it often initially manifests with cutaneous involvement with noncaseating “naked” granulomas in the dermis and subcutaneous tissue. Although TAGU cases have demonstrated noncaseating granulomas in association with dermal tattoo pigment on histopathology,^1,4 dermal lymphoplasmacytic inflammation with scattered foreign body giant cells was noted in our patient, which was more consistent with allergic contact dermatitis. Thus, it is important to consider that TAGU can be seen with varying histologic patterns. In patients with tattoos, sarcoidosis can manifest grossly as a papulonodular cutaneous reaction.⁵ Active smoking is associated with a decreased risk for sarcoidosis, and those who smoke are statistically more likely to have tattoos than the general population,^6,7 so our patient’s smoking history may be relevant. However, sarcoidosis was an unlikely diagnosis due to the serum angiotensin-converting enzyme level; results of a chest radiograph (bilateral adenopathy and coarse reticular opacities) and computed tomography (hilar and mediastinal adenopathy); and nonsarcoidal histopathology.

An allergic reaction to tattoo ink is caused by a delayed-type hypersensitivity reaction to a pigment hapten that can develop abruptly months to years after tattoo placement—1 year after tattoo placement in our patient. This reaction was seen in our patient’s blue pigment tattoos, although it is more commonly seen in red pigment tattoos.⁸ Although the etiology of TAGU is poorly understood, it also is hypothesized to be a delayed-type hypersensitivity response to tattoo ink particles, suggested by the pattern of lymphocytes infiltrating the tattoo and atypical T-cell infiltrate on vitreous biopsy.^9,10 Further research is required to elucidate the relationship between tattoos and uveitis.

Q-switched lasers (eg, 532-nm or 1064-nm Nd:YAG, alexandrite, or ruby lasers) are the standard treatment options for uncomplicated tattoo removal and employ a high-intensity, ultrashort pulse duration.¹¹ However Q-switched lasers require multiple sessions and target pigment-containing cells, releasing the tattoo particles into systemic circulation, which can potentially induce a severe allergic response.¹² In contrast, CO₂ lasers use a different mechanism, emitting energy at a wavelength of 10,600 nm, which is absorbed by intracellular water and allows for the ablation of the superficial epidermis along with the embedded ink with subsequent re-epithelialization, as well as heat-mediated thermal injury to allow for dermal collagen remodeling.¹³ In a 2021 retrospective study of ablative laser therapy for allergic tattoo reactions, patients were treated with the 10,600-nm ablative CO₂ laser and noted improvements in itching and burning with minimal adverse events.¹² Although using a CO₂ laser may not be considered a firstline treatment option for TAGU, the refractory clinical course and notable morbidity of surgical excision necessitated the use of ablative laser in our case.

Tattoo granulomas with uveitis is a rare diagnosis with the potential for serious permanent sequelae including blindness. Existing treatments such as topical and oral corticosteroids, immunosuppressants, surgical excision, and Q-switched lasers all are possible options, but in a patient with progressive ocular symptoms with other potential rheumatologic conditions and sarcoidosis ruled out, fully ablative CO₂ laser may be an effective treatment option. Our case demonstrated the successful treatment of TAGU with CO₂ laser ablation. Given the unclear etiology of TAGU and the limited evidence on treatment options and efficacy, our case contributes to the body of literature that can inform clinical management of this unusual and serious reaction.

To the Editor:

A 22-year-old man was referred to our dermatology outpatient department for wartlike growths that gradually developed around a postoperative enteroatmospheric fistula and stoma over the past 4 months. The patient presented for an emergency exploratory laparotomy with a history of perforation peritonitis 1.5 years prior to the current presentation. He also had a small bowel obstruction 5 months prior to the current presentation that resulted in the resection of a large segment of the small bowel. He underwent a diverting loop ileostomy when the abdominal closure was not achieved because of bowel edema, following which he developed a postoperative enteroatmospheric fistula. In addition, the stoma retracted and was followed by dermal dehiscence, which led to notable leakage and resulted in heavy fecal contamination of the midline wound.

At the current presentation, physical examination revealed multiple grayish-white, dome-shaped, moist papules coalescing to form a peristomal pseudoverrucous mass on the lower side of the stoma (Figure 1). The patient experienced mild itching. The lesion showed no signs of erosion, bleeding, or purulent discharge, and there were no nearby lumps or enlarged lymph nodes. The differential diagnosis included peristomal pyoderma gangrenosum, human papillomavirus (HPV) infection, pseudoverrucous papules and nodules (PPNs), squamous cell carcinoma, and exuberant granulation tissue. A skin biopsy was performed, and histopathology revealed hyperkeratosis, moderate papillomatosis, and marked acanthotic hyperplasia seen as downgrowths into the dermis (Figure 2). No koilocytes, atypia, or mitotic figures were present. Abundant neutrophils and few eosinophils were seen in the dermal infiltrate. A final diagnosis of PPN was made based on clinicopathologic correlation. The patient was advised to use a smaller stoma bag and to change the collection pouch frequently to reduce skin contact with fecal matter.

Peristomal skin conditions are reported in 18% to 55% of patients with stomas and include allergic contact dermatitis, mechanical dermatitis, infections, pyoderma gangrenosum, and irritant contact dermatitis.^1,2 Pseudoverrucous papules (also called chronic papillomatous dermatitis or pseudoverrucous lesions) is a rare dermatologic complication found on the skin around stomas,³ most commonly around urostomy stomas. The presence of PPNs around colostomy stomas and the perianal region is extremely rare.^2,4 This condition is the result of chronic irritant dermatitis from frequent exposure to urine or feces, leading to maceration and epidermal hyperplasia. It occurs because of improper sizing of the stoma bag or incorrect positioning or construction of the stoma.⁵

the overuse of topical benzocaine-resorcinol, leading to chronic irritation.⁶ It is clinically characterized by multiple grayish-white, wartlike, confluent papulonodules around areas chronically exposed to moisture. Differential diagnoses such as secondary neoplasms, HPV infection, exuberant granulation tissue, and candidal infections should be considered.³ Final diagnosis is based on clinicopathologic findings, similar to our case. Epidermal growth factor and transforming growth factor are thought to play a role in the pathophysiology of pseudoepitheliomatous hyperplasia. Increased expression of these mediators leads to proliferation of the epidermis into the dermis.⁷ The role of HPV in PPN remains unclear, as not all PPN lesions are positive for HPV and the cutaneous lesions resolve once the source of irritation is removed. Recommended treatment includes local skin care; stoma refitting; and, in severe cases, excision and revision of the stoma.² Dermatologists must be aware of this often-underdiagnosed condition.

To the Editor:

A 22-year-old man was referred to our dermatology outpatient department for wartlike growths that gradually developed around a postoperative enteroatmospheric fistula and stoma over the past 4 months. The patient presented for an emergency exploratory laparotomy with a history of perforation peritonitis 1.5 years prior to the current presentation. He also had a small bowel obstruction 5 months prior to the current presentation that resulted in the resection of a large segment of the small bowel. He underwent a diverting loop ileostomy when the abdominal closure was not achieved because of bowel edema, following which he developed a postoperative enteroatmospheric fistula. In addition, the stoma retracted and was followed by dermal dehiscence, which led to notable leakage and resulted in heavy fecal contamination of the midline wound.

At the current presentation, physical examination revealed multiple grayish-white, dome-shaped, moist papules coalescing to form a peristomal pseudoverrucous mass on the lower side of the stoma (Figure 1). The patient experienced mild itching. The lesion showed no signs of erosion, bleeding, or purulent discharge, and there were no nearby lumps or enlarged lymph nodes. The differential diagnosis included peristomal pyoderma gangrenosum, human papillomavirus (HPV) infection, pseudoverrucous papules and nodules (PPNs), squamous cell carcinoma, and exuberant granulation tissue. A skin biopsy was performed, and histopathology revealed hyperkeratosis, moderate papillomatosis, and marked acanthotic hyperplasia seen as downgrowths into the dermis (Figure 2). No koilocytes, atypia, or mitotic figures were present. Abundant neutrophils and few eosinophils were seen in the dermal infiltrate. A final diagnosis of PPN was made based on clinicopathologic correlation. The patient was advised to use a smaller stoma bag and to change the collection pouch frequently to reduce skin contact with fecal matter.

Peristomal skin conditions are reported in 18% to 55% of patients with stomas and include allergic contact dermatitis, mechanical dermatitis, infections, pyoderma gangrenosum, and irritant contact dermatitis.^1,2 Pseudoverrucous papules (also called chronic papillomatous dermatitis or pseudoverrucous lesions) is a rare dermatologic complication found on the skin around stomas,³ most commonly around urostomy stomas. The presence of PPNs around colostomy stomas and the perianal region is extremely rare.^2,4 This condition is the result of chronic irritant dermatitis from frequent exposure to urine or feces, leading to maceration and epidermal hyperplasia. It occurs because of improper sizing of the stoma bag or incorrect positioning or construction of the stoma.⁵

the overuse of topical benzocaine-resorcinol, leading to chronic irritation.⁶ It is clinically characterized by multiple grayish-white, wartlike, confluent papulonodules around areas chronically exposed to moisture. Differential diagnoses such as secondary neoplasms, HPV infection, exuberant granulation tissue, and candidal infections should be considered.³ Final diagnosis is based on clinicopathologic findings, similar to our case. Epidermal growth factor and transforming growth factor are thought to play a role in the pathophysiology of pseudoepitheliomatous hyperplasia. Increased expression of these mediators leads to proliferation of the epidermis into the dermis.⁷ The role of HPV in PPN remains unclear, as not all PPN lesions are positive for HPV and the cutaneous lesions resolve once the source of irritation is removed. Recommended treatment includes local skin care; stoma refitting; and, in severe cases, excision and revision of the stoma.² Dermatologists must be aware of this often-underdiagnosed condition.

To the Editor:

A 22-year-old man was referred to our dermatology outpatient department for wartlike growths that gradually developed around a postoperative enteroatmospheric fistula and stoma over the past 4 months. The patient presented for an emergency exploratory laparotomy with a history of perforation peritonitis 1.5 years prior to the current presentation. He also had a small bowel obstruction 5 months prior to the current presentation that resulted in the resection of a large segment of the small bowel. He underwent a diverting loop ileostomy when the abdominal closure was not achieved because of bowel edema, following which he developed a postoperative enteroatmospheric fistula. In addition, the stoma retracted and was followed by dermal dehiscence, which led to notable leakage and resulted in heavy fecal contamination of the midline wound.

At the current presentation, physical examination revealed multiple grayish-white, dome-shaped, moist papules coalescing to form a peristomal pseudoverrucous mass on the lower side of the stoma (Figure 1). The patient experienced mild itching. The lesion showed no signs of erosion, bleeding, or purulent discharge, and there were no nearby lumps or enlarged lymph nodes. The differential diagnosis included peristomal pyoderma gangrenosum, human papillomavirus (HPV) infection, pseudoverrucous papules and nodules (PPNs), squamous cell carcinoma, and exuberant granulation tissue. A skin biopsy was performed, and histopathology revealed hyperkeratosis, moderate papillomatosis, and marked acanthotic hyperplasia seen as downgrowths into the dermis (Figure 2). No koilocytes, atypia, or mitotic figures were present. Abundant neutrophils and few eosinophils were seen in the dermal infiltrate. A final diagnosis of PPN was made based on clinicopathologic correlation. The patient was advised to use a smaller stoma bag and to change the collection pouch frequently to reduce skin contact with fecal matter.

Peristomal skin conditions are reported in 18% to 55% of patients with stomas and include allergic contact dermatitis, mechanical dermatitis, infections, pyoderma gangrenosum, and irritant contact dermatitis.^1,2 Pseudoverrucous papules (also called chronic papillomatous dermatitis or pseudoverrucous lesions) is a rare dermatologic complication found on the skin around stomas,³ most commonly around urostomy stomas. The presence of PPNs around colostomy stomas and the perianal region is extremely rare.^2,4 This condition is the result of chronic irritant dermatitis from frequent exposure to urine or feces, leading to maceration and epidermal hyperplasia. It occurs because of improper sizing of the stoma bag or incorrect positioning or construction of the stoma.⁵

the overuse of topical benzocaine-resorcinol, leading to chronic irritation.⁶ It is clinically characterized by multiple grayish-white, wartlike, confluent papulonodules around areas chronically exposed to moisture. Differential diagnoses such as secondary neoplasms, HPV infection, exuberant granulation tissue, and candidal infections should be considered.³ Final diagnosis is based on clinicopathologic findings, similar to our case. Epidermal growth factor and transforming growth factor are thought to play a role in the pathophysiology of pseudoepitheliomatous hyperplasia. Increased expression of these mediators leads to proliferation of the epidermis into the dermis.⁷ The role of HPV in PPN remains unclear, as not all PPN lesions are positive for HPV and the cutaneous lesions resolve once the source of irritation is removed. Recommended treatment includes local skin care; stoma refitting; and, in severe cases, excision and revision of the stoma.² Dermatologists must be aware of this often-underdiagnosed condition.

To the Editor:

Idiopathic gingival papillokeratosis with crypt formation (IGPC) is an uncommon benign condition that first was reported in 1967.¹ The condition manifests as white plaques with a papillary appearance on the gingival tissue. While data on the prevalence of IGPC are limited, it is known to occur more frequently in younger patients (ie, 9-24 years^1-3) and has been linked to use of orthodontic appliances.^3,4 The lesions typically are asymptomatic with a bilateral appearance along the mucogingival junction. Research on IGPC has not identified the underlying mechanisms that trigger the hyperkeratinization and papillary alterations within the gingival tissue.

Management of IGPC can be challenging due to the rarity of the condition and its uncertain pathogenesis. Wiping or brushing the affected area offers only temporary improvement of symptoms and the appearance of the lesions. Surgical excision is another option; however, it can result in aesthetic and/or functional periodontal defects.² Alternately, employing methods such as wiping or brushing the affected area offers only transient and temporary results in managing the condition. Additional investigative approaches and clinical studies are needed to identify more effective therapeutic modalities for the management of IGPC, particularly in pediatric patients, in whom aesthetic results may take on a heightened importance.^1-3 We report a case of IGPC in which cryotherapy yielded satisfactory results with no recurrence of the lesions.

A 32-year-old woman presented to the dental clinic with white spots on the gingiva of 5 months’ duration. The patient reported a history of smoking cigarettes (3 packs per year) and drinking alcohol in social situations; her medical history was otherwise unremarkable. Clinical examination of the oral cavity revealed a bilateral, irregular, verrucouslike plaque throughout the vestibular upper attached gingiva. An incisional biopsy from the attached gingiva between teeth 13 and 23 was performed. Histopathologic analysis revealed parakeratosis and papillary acanthosis of the gingival mucosa associated with multifocal epithelial invaginations resembling crypts as well as long tapered epithelial ridges with no inflammation in the lamina propria. Based on the histopathologic findings, a diagnosis of IGPC was made (Figure 1).

Given the patient’s clinical presentation, we suggested treatment with cryotherapy as a minimally invasive option that would preserve the gingival architecture and aesthetics while avoiding the potential complications of surgical excision. The patient consented to the procedure, and liquid nitrogen was administered through a handheld device using a 0.6-mm aperture spray tip. During application, the spray tip was positioned at a distance of 0.5 to 1.0 cm from the labial marginal gingiva at about a 45° angle. The freeze/thaw cycle involved a continuous one-way spray application of liquid nitrogen onto the lesion until solid ice formed over the entire area, followed by a waiting period until gradual thawing occurred.

A total of 5 cryotherapy sessions were conducted over an 8-week period; no recurrence of the lesions was observed during a 2-year follow-up period (Figure 2).

We present our case to add to the body of knowledge regarding management options for IGPC, specifically cryotherapy. Historically, brushing with a toothbrush and surgical excision have been the most commonly used interventions.² Gently brushing the affected areas can help stimulate local blood circulation, which can improve the health of the gingival tissue, promote oxygenation and delivery of nutrients to the cells, and aid in the removal of metabolic waste. Surgical excision is the most commonly used treatment method for IGPC to ensure that the lesions are safely and completely removed; however, this option can result in aesthetic and/or functional periodontal defects. There also is a risk for recurrence, although Noonan et al² reported no recurrence 4 years after performing a surgical excision for IGPC.

Cryotherapy reduces tissue sensitivity, provides local anesthesia, and reduces inflammation in the oral mucosa. Moreover, cryotherapy accelerates healing by stimulating vasoconstriction and reactive vasodilation, thus enhancing blood flow, oxygenation, and nutrient delivery for faster cell regeneration of the oral mucosa.^4,5 Cryotherapy generally is regarded as a simple noninvasive procedure that is relatively safe when performed by qualified professionals.^4,5 It can provide benefits such as minimal patient discomfort, rapid recovery, and potential reduction of complications associated with more invasive procedures.⁵

The efficacy of cryotherapy for IGPC may vary based on lesion severity, individual patient response, and the need for repeated treatment sessions. Robust scientific evidence concerning the long-term efficacy of cryotherapy as a treatment for IGPC is limited due to the rarity of this condition.

The etiopathogenesis of IGPC has been hypothesized to involve both genetic and environmental factors with equal significance. This suggestion is based on reports of IGPC occurring in multiple members of the same family and animal model studies indicating that gingival tissue is sensitive to environmental influences, such as nutritional factors.^1,6 However, it is important to emphasize that these hypotheses remain speculative, and the true etiopathogenesis of IGPC remains uncertain.⁶ Microscopically, biopsy fragments from suspected cases of IGPC reveal gingival mucosa characterized by parakeratosis and papillary acanthosis accompanied by multifocal epithelial invaginations resembling crypts.² Additionally, elongated and tapered epithelial ridges without inflammation in the lamina propria may be observed (as in our case), favoring the diagnosis of IGPC.³ The absence of inflammation is noteworthy because it suggests that the observed alterations are not attributed to typical inflammatory processes seen in some gingival conditions.

The limited number of studies reporting successful treatment outcomes with long-term follow-up for IGPC cases underscores the need for further exploration of effective treatment options. Cryotherapy emerges as a promising minimally invasive therapeutic approach, with our case offering support for its potential application. Additional research and clinical trials are essential to validate its efficacy and improve our understanding of cryotherapy as a treatment modality for IGPC lesions.

To the Editor:

Idiopathic gingival papillokeratosis with crypt formation (IGPC) is an uncommon benign condition that first was reported in 1967.¹ The condition manifests as white plaques with a papillary appearance on the gingival tissue. While data on the prevalence of IGPC are limited, it is known to occur more frequently in younger patients (ie, 9-24 years^1-3) and has been linked to use of orthodontic appliances.^3,4 The lesions typically are asymptomatic with a bilateral appearance along the mucogingival junction. Research on IGPC has not identified the underlying mechanisms that trigger the hyperkeratinization and papillary alterations within the gingival tissue.

Management of IGPC can be challenging due to the rarity of the condition and its uncertain pathogenesis. Wiping or brushing the affected area offers only temporary improvement of symptoms and the appearance of the lesions. Surgical excision is another option; however, it can result in aesthetic and/or functional periodontal defects.² Alternately, employing methods such as wiping or brushing the affected area offers only transient and temporary results in managing the condition. Additional investigative approaches and clinical studies are needed to identify more effective therapeutic modalities for the management of IGPC, particularly in pediatric patients, in whom aesthetic results may take on a heightened importance.^1-3 We report a case of IGPC in which cryotherapy yielded satisfactory results with no recurrence of the lesions.

A 32-year-old woman presented to the dental clinic with white spots on the gingiva of 5 months’ duration. The patient reported a history of smoking cigarettes (3 packs per year) and drinking alcohol in social situations; her medical history was otherwise unremarkable. Clinical examination of the oral cavity revealed a bilateral, irregular, verrucouslike plaque throughout the vestibular upper attached gingiva. An incisional biopsy from the attached gingiva between teeth 13 and 23 was performed. Histopathologic analysis revealed parakeratosis and papillary acanthosis of the gingival mucosa associated with multifocal epithelial invaginations resembling crypts as well as long tapered epithelial ridges with no inflammation in the lamina propria. Based on the histopathologic findings, a diagnosis of IGPC was made (Figure 1).

Given the patient’s clinical presentation, we suggested treatment with cryotherapy as a minimally invasive option that would preserve the gingival architecture and aesthetics while avoiding the potential complications of surgical excision. The patient consented to the procedure, and liquid nitrogen was administered through a handheld device using a 0.6-mm aperture spray tip. During application, the spray tip was positioned at a distance of 0.5 to 1.0 cm from the labial marginal gingiva at about a 45° angle. The freeze/thaw cycle involved a continuous one-way spray application of liquid nitrogen onto the lesion until solid ice formed over the entire area, followed by a waiting period until gradual thawing occurred.

A total of 5 cryotherapy sessions were conducted over an 8-week period; no recurrence of the lesions was observed during a 2-year follow-up period (Figure 2).

We present our case to add to the body of knowledge regarding management options for IGPC, specifically cryotherapy. Historically, brushing with a toothbrush and surgical excision have been the most commonly used interventions.² Gently brushing the affected areas can help stimulate local blood circulation, which can improve the health of the gingival tissue, promote oxygenation and delivery of nutrients to the cells, and aid in the removal of metabolic waste. Surgical excision is the most commonly used treatment method for IGPC to ensure that the lesions are safely and completely removed; however, this option can result in aesthetic and/or functional periodontal defects. There also is a risk for recurrence, although Noonan et al² reported no recurrence 4 years after performing a surgical excision for IGPC.

Cryotherapy reduces tissue sensitivity, provides local anesthesia, and reduces inflammation in the oral mucosa. Moreover, cryotherapy accelerates healing by stimulating vasoconstriction and reactive vasodilation, thus enhancing blood flow, oxygenation, and nutrient delivery for faster cell regeneration of the oral mucosa.^4,5 Cryotherapy generally is regarded as a simple noninvasive procedure that is relatively safe when performed by qualified professionals.^4,5 It can provide benefits such as minimal patient discomfort, rapid recovery, and potential reduction of complications associated with more invasive procedures.⁵

The efficacy of cryotherapy for IGPC may vary based on lesion severity, individual patient response, and the need for repeated treatment sessions. Robust scientific evidence concerning the long-term efficacy of cryotherapy as a treatment for IGPC is limited due to the rarity of this condition.

The etiopathogenesis of IGPC has been hypothesized to involve both genetic and environmental factors with equal significance. This suggestion is based on reports of IGPC occurring in multiple members of the same family and animal model studies indicating that gingival tissue is sensitive to environmental influences, such as nutritional factors.^1,6 However, it is important to emphasize that these hypotheses remain speculative, and the true etiopathogenesis of IGPC remains uncertain.⁶ Microscopically, biopsy fragments from suspected cases of IGPC reveal gingival mucosa characterized by parakeratosis and papillary acanthosis accompanied by multifocal epithelial invaginations resembling crypts.² Additionally, elongated and tapered epithelial ridges without inflammation in the lamina propria may be observed (as in our case), favoring the diagnosis of IGPC.³ The absence of inflammation is noteworthy because it suggests that the observed alterations are not attributed to typical inflammatory processes seen in some gingival conditions.

The limited number of studies reporting successful treatment outcomes with long-term follow-up for IGPC cases underscores the need for further exploration of effective treatment options. Cryotherapy emerges as a promising minimally invasive therapeutic approach, with our case offering support for its potential application. Additional research and clinical trials are essential to validate its efficacy and improve our understanding of cryotherapy as a treatment modality for IGPC lesions.

To the Editor:

Idiopathic gingival papillokeratosis with crypt formation (IGPC) is an uncommon benign condition that first was reported in 1967.¹ The condition manifests as white plaques with a papillary appearance on the gingival tissue. While data on the prevalence of IGPC are limited, it is known to occur more frequently in younger patients (ie, 9-24 years^1-3) and has been linked to use of orthodontic appliances.^3,4 The lesions typically are asymptomatic with a bilateral appearance along the mucogingival junction. Research on IGPC has not identified the underlying mechanisms that trigger the hyperkeratinization and papillary alterations within the gingival tissue.

Management of IGPC can be challenging due to the rarity of the condition and its uncertain pathogenesis. Wiping or brushing the affected area offers only temporary improvement of symptoms and the appearance of the lesions. Surgical excision is another option; however, it can result in aesthetic and/or functional periodontal defects.² Alternately, employing methods such as wiping or brushing the affected area offers only transient and temporary results in managing the condition. Additional investigative approaches and clinical studies are needed to identify more effective therapeutic modalities for the management of IGPC, particularly in pediatric patients, in whom aesthetic results may take on a heightened importance.^1-3 We report a case of IGPC in which cryotherapy yielded satisfactory results with no recurrence of the lesions.

A 32-year-old woman presented to the dental clinic with white spots on the gingiva of 5 months’ duration. The patient reported a history of smoking cigarettes (3 packs per year) and drinking alcohol in social situations; her medical history was otherwise unremarkable. Clinical examination of the oral cavity revealed a bilateral, irregular, verrucouslike plaque throughout the vestibular upper attached gingiva. An incisional biopsy from the attached gingiva between teeth 13 and 23 was performed. Histopathologic analysis revealed parakeratosis and papillary acanthosis of the gingival mucosa associated with multifocal epithelial invaginations resembling crypts as well as long tapered epithelial ridges with no inflammation in the lamina propria. Based on the histopathologic findings, a diagnosis of IGPC was made (Figure 1).

Given the patient’s clinical presentation, we suggested treatment with cryotherapy as a minimally invasive option that would preserve the gingival architecture and aesthetics while avoiding the potential complications of surgical excision. The patient consented to the procedure, and liquid nitrogen was administered through a handheld device using a 0.6-mm aperture spray tip. During application, the spray tip was positioned at a distance of 0.5 to 1.0 cm from the labial marginal gingiva at about a 45° angle. The freeze/thaw cycle involved a continuous one-way spray application of liquid nitrogen onto the lesion until solid ice formed over the entire area, followed by a waiting period until gradual thawing occurred.

A total of 5 cryotherapy sessions were conducted over an 8-week period; no recurrence of the lesions was observed during a 2-year follow-up period (Figure 2).

We present our case to add to the body of knowledge regarding management options for IGPC, specifically cryotherapy. Historically, brushing with a toothbrush and surgical excision have been the most commonly used interventions.² Gently brushing the affected areas can help stimulate local blood circulation, which can improve the health of the gingival tissue, promote oxygenation and delivery of nutrients to the cells, and aid in the removal of metabolic waste. Surgical excision is the most commonly used treatment method for IGPC to ensure that the lesions are safely and completely removed; however, this option can result in aesthetic and/or functional periodontal defects. There also is a risk for recurrence, although Noonan et al² reported no recurrence 4 years after performing a surgical excision for IGPC.

Cryotherapy reduces tissue sensitivity, provides local anesthesia, and reduces inflammation in the oral mucosa. Moreover, cryotherapy accelerates healing by stimulating vasoconstriction and reactive vasodilation, thus enhancing blood flow, oxygenation, and nutrient delivery for faster cell regeneration of the oral mucosa.^4,5 Cryotherapy generally is regarded as a simple noninvasive procedure that is relatively safe when performed by qualified professionals.^4,5 It can provide benefits such as minimal patient discomfort, rapid recovery, and potential reduction of complications associated with more invasive procedures.⁵

The efficacy of cryotherapy for IGPC may vary based on lesion severity, individual patient response, and the need for repeated treatment sessions. Robust scientific evidence concerning the long-term efficacy of cryotherapy as a treatment for IGPC is limited due to the rarity of this condition.

The etiopathogenesis of IGPC has been hypothesized to involve both genetic and environmental factors with equal significance. This suggestion is based on reports of IGPC occurring in multiple members of the same family and animal model studies indicating that gingival tissue is sensitive to environmental influences, such as nutritional factors.^1,6 However, it is important to emphasize that these hypotheses remain speculative, and the true etiopathogenesis of IGPC remains uncertain.⁶ Microscopically, biopsy fragments from suspected cases of IGPC reveal gingival mucosa characterized by parakeratosis and papillary acanthosis accompanied by multifocal epithelial invaginations resembling crypts.² Additionally, elongated and tapered epithelial ridges without inflammation in the lamina propria may be observed (as in our case), favoring the diagnosis of IGPC.³ The absence of inflammation is noteworthy because it suggests that the observed alterations are not attributed to typical inflammatory processes seen in some gingival conditions.

The limited number of studies reporting successful treatment outcomes with long-term follow-up for IGPC cases underscores the need for further exploration of effective treatment options. Cryotherapy emerges as a promising minimally invasive therapeutic approach, with our case offering support for its potential application. Additional research and clinical trials are essential to validate its efficacy and improve our understanding of cryotherapy as a treatment modality for IGPC lesions.

To the Editor:

Cutaneous metastasis of prostate cancer is rare and portends a bleak prognosis. Diagnosis of the primary cancer can be challenging, as skin metastasis can mimic a variety of conditions. We report a case of metastatic prostatic adenocarcinoma confirmed via biopsy of a new skin lesion.

A 97-year-old man presented to the dermatology clinic for routine follow-up of psoriasis. During the visit, a family member mentioned a new bleeding lesion on the left shoulder. It was not known how long the lesion had been present. Four months prior, the patient had a prostate-specific antigen (PSA) level of 582 ng/mL (reference range, 0-6.5 ng/mL), and computed tomography of the chest had shown innumerable pulmonary nodules in addition to lymphadenopathy of the left axilla, clavicle, and mediastinum. The imaging was ordered by the patient’s urologist as part of routine workup, as he had a history of obstructive renal failure and was being monitored for an indwelling catheter. Two months later, a bone scan ordered by the urologist due to high PSA levels showed extensive osteoblastic metastatic disease throughout the axial and proximal appendicular skeleton. The elevated PSA levels and findings of pulmonary and osteoblastic metastasis suggested a diagnosis of metastatic prostatic adenocarcinoma, but no confirmatory biopsy was performed following the imaging because the patient’s family declined additional workup or intervention.

Physical examination at the current presentation revealed an 8-mm brown papule with an overlying blue-white veil (Figure 1). There were no other skin findings. Primary differential diagnoses included metastatic prostate cancer, nodular melanoma, and traumatized seborrheic keratosis. A shave biopsy of the lesion showed multiple glandular structures infiltrating the dermis lined by monomorphic epithelial cells with prominent eosinophilic nucleoli (Figures 2 and 3). Focal cribriform architecture of the glands was present as well as dermal hemorrhage and a lymphohistiocytic infiltrate (Figure 2A). Interestingly, in-transit vascular metastases were confirmed with the support of ERG, CD34, and CD31 immunohistochemical staining of the vessels.

Immunohistochemical staining was positive for PSA (Figure 2B), NKX 3.1, and ERG in the invasive glandular structures, which also displayed patchy weak staining with AMACR. Staining was negative for prostein, cytokeratin (CK) 7, CK20, CK5/6, p63, p40, CDX2, and thyroid transcription factor 1. These findings were consistent with a diagnosis of cutaneous metastatic prostatic adenocarcinoma. Next-generation sequencing showed trans-membrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG) fusion compatible with the positive ERG immunohistochemical staining. The patient and family declined any treatment due to his age, comorbidities, and rapid decline. He died 2 months after diagnosis of the skin metastasis.

Aside from nonmelanoma skin cancer, prostate cancer is the most common cancer and the second leading cause of cancer-related deaths among men in the United States.¹ It most commonly metastasizes to the bones, nonregional lymph nodes, liver, and thorax.² Metastasis to the skin is very rare, with only a 0.36% incidence.³ When prostate cancer does metastasize to the skin, the prognosis is poor, with an estimated mean survival of 7 months after diagnosis of cutaneous metastasis.⁴ Our patient’s survival time was even shorter—only 2 months after diagnosis of cutaneous metastasis, likely the result of his late diagnosis.

Clinically, cutaneous metastasis of prostate cancer can manifest as a wide variety of lesions; in one report of 78 cases, 56 (72%) were hard nodules, 11 (14%) were single nodules, 5 (7%) were edema or lymphedema, and 5 (7%) were an unspecific rash.⁴ Diagnosis of cutaneous metastasis of prostate cancer can be challenging, as it often is mistaken for other skin conditions including herpes zoster, basal cell carcinoma, angiosarcoma, cellulitis, mammary Paget disease, telangiectasia, pyoderma, morphea, and trichoepithelioma.⁵ In our patient, the clinical appearance of the lesion resembled a nodular melanoma. Thus, in patients with a history of prostate cancer, it is important to keep cutaneous metastasis in the differential when examining the skin because of the prognostic implications. Cutaneous metastasis of prostate cancer often indicates a poor prognosis.

In a report of 78 patients, the most common sites of skin metastasis for prostate cancer were the inguinal area and penis (28% [22/78]), abdomen (23% [18/78]), head and neck (16% [12/78]), and chest (14% [11/78]); the extremities and back were less frequently involved (10% [8/78] and 9% [7/78], respectively).⁴ Generally, cutaneous metastasis of internal malignancies involves the deep dermis and the subcutaneous tissue. It is common for cutaneous metastases to show histologic features of the primary tumor, as we saw in our patient. In a case series with 45 histologic diagnoses of cutaneous metastases from internal malignancies, 75.5% (34/45) of cases showed morphologic features of the primary tumor.⁶ However, this is not always the case, and the histologic appearance may vary. Metastatic prostate cancer may manifest as sheets, nests, or cords and often may have nuclear pleomorphism with prominent nucleoli.⁷

Immunohistochemical staining can help make a definitive diagnosis and differentiate the source of the tumor. Prostate cancer metastases often will stain positive for NKX3.1, PSA, AMACR, ERG, PSMA, and prosaposin, with PSA being the most specific marker.^7,8 In our patient, no prostate biopsy had been performed, thus the skin biopsy was the diagnostic tissue for the prostatic adenocarcinoma.

Next-generation sequencing showed a TMPRSS2- ERG fusion, which commonly is seen in prostate cancer.⁹ A search of Google Scholar using the terms next-generation sequencing, cutaneous metastasis, and prostate adenocarcinoma yielded 3 additional cases of cutaneous metastasis of prostate cancer in which next-generation sequencing was performed.^10-12 One case showed mutations of the tumor protein 53 (TP53) and phosphatase and tensin homolog (PTEN) genes; one showed just a TP53 mutation; and one showed inactivation of the breast cancer predisposition gene 2 (BRCA2) and amplification of MYC proto-oncogene, BHLH transcription factor (MYC) and fibroblast growth factor receptor 1 (FGFR1).^10,11,12 While limited by a small number of reported cases, there does not appear to be a repeating mutation to suggest a genetic mechanism of skin metastasis.

The route of cutaneous metastasis of prostate cancer still is unclear, but hypothesized mechanisms include hematogenous or lymphatic spread, direct infiltration, or implantation from a surgical scar.¹¹ When cutaneous involvement occurs in an area far from the primary tumor, it is thought to be the result of hematogenous spread, which would be consistent with our patient’s findings.¹³ Given the role of Batson venous plexus as a conduit from the prostate to the vertebral column for metastatic spread and considering the location of the lesion on our patient’s back, we hypothesized that the mechanism of metastasis to the skin was from vascular extension of the metastatic foci involving the vertebrae.

Our case highlights the importance of considering cutaneous involvement of prostatic adenocarcinoma in patients with new skin lesions, particularly in the setting of a known or suspected prostate malignancy. Skin metastasis can have a range of manifestations and provides prognostic information that can help determine the course of treatment.

To the Editor:

Cutaneous metastasis of prostate cancer is rare and portends a bleak prognosis. Diagnosis of the primary cancer can be challenging, as skin metastasis can mimic a variety of conditions. We report a case of metastatic prostatic adenocarcinoma confirmed via biopsy of a new skin lesion.

A 97-year-old man presented to the dermatology clinic for routine follow-up of psoriasis. During the visit, a family member mentioned a new bleeding lesion on the left shoulder. It was not known how long the lesion had been present. Four months prior, the patient had a prostate-specific antigen (PSA) level of 582 ng/mL (reference range, 0-6.5 ng/mL), and computed tomography of the chest had shown innumerable pulmonary nodules in addition to lymphadenopathy of the left axilla, clavicle, and mediastinum. The imaging was ordered by the patient’s urologist as part of routine workup, as he had a history of obstructive renal failure and was being monitored for an indwelling catheter. Two months later, a bone scan ordered by the urologist due to high PSA levels showed extensive osteoblastic metastatic disease throughout the axial and proximal appendicular skeleton. The elevated PSA levels and findings of pulmonary and osteoblastic metastasis suggested a diagnosis of metastatic prostatic adenocarcinoma, but no confirmatory biopsy was performed following the imaging because the patient’s family declined additional workup or intervention.

Physical examination at the current presentation revealed an 8-mm brown papule with an overlying blue-white veil (Figure 1). There were no other skin findings. Primary differential diagnoses included metastatic prostate cancer, nodular melanoma, and traumatized seborrheic keratosis. A shave biopsy of the lesion showed multiple glandular structures infiltrating the dermis lined by monomorphic epithelial cells with prominent eosinophilic nucleoli (Figures 2 and 3). Focal cribriform architecture of the glands was present as well as dermal hemorrhage and a lymphohistiocytic infiltrate (Figure 2A). Interestingly, in-transit vascular metastases were confirmed with the support of ERG, CD34, and CD31 immunohistochemical staining of the vessels.

Immunohistochemical staining was positive for PSA (Figure 2B), NKX 3.1, and ERG in the invasive glandular structures, which also displayed patchy weak staining with AMACR. Staining was negative for prostein, cytokeratin (CK) 7, CK20, CK5/6, p63, p40, CDX2, and thyroid transcription factor 1. These findings were consistent with a diagnosis of cutaneous metastatic prostatic adenocarcinoma. Next-generation sequencing showed trans-membrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG) fusion compatible with the positive ERG immunohistochemical staining. The patient and family declined any treatment due to his age, comorbidities, and rapid decline. He died 2 months after diagnosis of the skin metastasis.

Aside from nonmelanoma skin cancer, prostate cancer is the most common cancer and the second leading cause of cancer-related deaths among men in the United States.¹ It most commonly metastasizes to the bones, nonregional lymph nodes, liver, and thorax.² Metastasis to the skin is very rare, with only a 0.36% incidence.³ When prostate cancer does metastasize to the skin, the prognosis is poor, with an estimated mean survival of 7 months after diagnosis of cutaneous metastasis.⁴ Our patient’s survival time was even shorter—only 2 months after diagnosis of cutaneous metastasis, likely the result of his late diagnosis.

Clinically, cutaneous metastasis of prostate cancer can manifest as a wide variety of lesions; in one report of 78 cases, 56 (72%) were hard nodules, 11 (14%) were single nodules, 5 (7%) were edema or lymphedema, and 5 (7%) were an unspecific rash.⁴ Diagnosis of cutaneous metastasis of prostate cancer can be challenging, as it often is mistaken for other skin conditions including herpes zoster, basal cell carcinoma, angiosarcoma, cellulitis, mammary Paget disease, telangiectasia, pyoderma, morphea, and trichoepithelioma.⁵ In our patient, the clinical appearance of the lesion resembled a nodular melanoma. Thus, in patients with a history of prostate cancer, it is important to keep cutaneous metastasis in the differential when examining the skin because of the prognostic implications. Cutaneous metastasis of prostate cancer often indicates a poor prognosis.

In a report of 78 patients, the most common sites of skin metastasis for prostate cancer were the inguinal area and penis (28% [22/78]), abdomen (23% [18/78]), head and neck (16% [12/78]), and chest (14% [11/78]); the extremities and back were less frequently involved (10% [8/78] and 9% [7/78], respectively).⁴ Generally, cutaneous metastasis of internal malignancies involves the deep dermis and the subcutaneous tissue. It is common for cutaneous metastases to show histologic features of the primary tumor, as we saw in our patient. In a case series with 45 histologic diagnoses of cutaneous metastases from internal malignancies, 75.5% (34/45) of cases showed morphologic features of the primary tumor.⁶ However, this is not always the case, and the histologic appearance may vary. Metastatic prostate cancer may manifest as sheets, nests, or cords and often may have nuclear pleomorphism with prominent nucleoli.⁷

Immunohistochemical staining can help make a definitive diagnosis and differentiate the source of the tumor. Prostate cancer metastases often will stain positive for NKX3.1, PSA, AMACR, ERG, PSMA, and prosaposin, with PSA being the most specific marker.^7,8 In our patient, no prostate biopsy had been performed, thus the skin biopsy was the diagnostic tissue for the prostatic adenocarcinoma.

Next-generation sequencing showed a TMPRSS2- ERG fusion, which commonly is seen in prostate cancer.⁹ A search of Google Scholar using the terms next-generation sequencing, cutaneous metastasis, and prostate adenocarcinoma yielded 3 additional cases of cutaneous metastasis of prostate cancer in which next-generation sequencing was performed.^10-12 One case showed mutations of the tumor protein 53 (TP53) and phosphatase and tensin homolog (PTEN) genes; one showed just a TP53 mutation; and one showed inactivation of the breast cancer predisposition gene 2 (BRCA2) and amplification of MYC proto-oncogene, BHLH transcription factor (MYC) and fibroblast growth factor receptor 1 (FGFR1).^10,11,12 While limited by a small number of reported cases, there does not appear to be a repeating mutation to suggest a genetic mechanism of skin metastasis.

The route of cutaneous metastasis of prostate cancer still is unclear, but hypothesized mechanisms include hematogenous or lymphatic spread, direct infiltration, or implantation from a surgical scar.¹¹ When cutaneous involvement occurs in an area far from the primary tumor, it is thought to be the result of hematogenous spread, which would be consistent with our patient’s findings.¹³ Given the role of Batson venous plexus as a conduit from the prostate to the vertebral column for metastatic spread and considering the location of the lesion on our patient’s back, we hypothesized that the mechanism of metastasis to the skin was from vascular extension of the metastatic foci involving the vertebrae.

Our case highlights the importance of considering cutaneous involvement of prostatic adenocarcinoma in patients with new skin lesions, particularly in the setting of a known or suspected prostate malignancy. Skin metastasis can have a range of manifestations and provides prognostic information that can help determine the course of treatment.

To the Editor:

Cutaneous metastasis of prostate cancer is rare and portends a bleak prognosis. Diagnosis of the primary cancer can be challenging, as skin metastasis can mimic a variety of conditions. We report a case of metastatic prostatic adenocarcinoma confirmed via biopsy of a new skin lesion.

A 97-year-old man presented to the dermatology clinic for routine follow-up of psoriasis. During the visit, a family member mentioned a new bleeding lesion on the left shoulder. It was not known how long the lesion had been present. Four months prior, the patient had a prostate-specific antigen (PSA) level of 582 ng/mL (reference range, 0-6.5 ng/mL), and computed tomography of the chest had shown innumerable pulmonary nodules in addition to lymphadenopathy of the left axilla, clavicle, and mediastinum. The imaging was ordered by the patient’s urologist as part of routine workup, as he had a history of obstructive renal failure and was being monitored for an indwelling catheter. Two months later, a bone scan ordered by the urologist due to high PSA levels showed extensive osteoblastic metastatic disease throughout the axial and proximal appendicular skeleton. The elevated PSA levels and findings of pulmonary and osteoblastic metastasis suggested a diagnosis of metastatic prostatic adenocarcinoma, but no confirmatory biopsy was performed following the imaging because the patient’s family declined additional workup or intervention.

Physical examination at the current presentation revealed an 8-mm brown papule with an overlying blue-white veil (Figure 1). There were no other skin findings. Primary differential diagnoses included metastatic prostate cancer, nodular melanoma, and traumatized seborrheic keratosis. A shave biopsy of the lesion showed multiple glandular structures infiltrating the dermis lined by monomorphic epithelial cells with prominent eosinophilic nucleoli (Figures 2 and 3). Focal cribriform architecture of the glands was present as well as dermal hemorrhage and a lymphohistiocytic infiltrate (Figure 2A). Interestingly, in-transit vascular metastases were confirmed with the support of ERG, CD34, and CD31 immunohistochemical staining of the vessels.

Immunohistochemical staining was positive for PSA (Figure 2B), NKX 3.1, and ERG in the invasive glandular structures, which also displayed patchy weak staining with AMACR. Staining was negative for prostein, cytokeratin (CK) 7, CK20, CK5/6, p63, p40, CDX2, and thyroid transcription factor 1. These findings were consistent with a diagnosis of cutaneous metastatic prostatic adenocarcinoma. Next-generation sequencing showed trans-membrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG) fusion compatible with the positive ERG immunohistochemical staining. The patient and family declined any treatment due to his age, comorbidities, and rapid decline. He died 2 months after diagnosis of the skin metastasis.

Aside from nonmelanoma skin cancer, prostate cancer is the most common cancer and the second leading cause of cancer-related deaths among men in the United States.¹ It most commonly metastasizes to the bones, nonregional lymph nodes, liver, and thorax.² Metastasis to the skin is very rare, with only a 0.36% incidence.³ When prostate cancer does metastasize to the skin, the prognosis is poor, with an estimated mean survival of 7 months after diagnosis of cutaneous metastasis.⁴ Our patient’s survival time was even shorter—only 2 months after diagnosis of cutaneous metastasis, likely the result of his late diagnosis.

Clinically, cutaneous metastasis of prostate cancer can manifest as a wide variety of lesions; in one report of 78 cases, 56 (72%) were hard nodules, 11 (14%) were single nodules, 5 (7%) were edema or lymphedema, and 5 (7%) were an unspecific rash.⁴ Diagnosis of cutaneous metastasis of prostate cancer can be challenging, as it often is mistaken for other skin conditions including herpes zoster, basal cell carcinoma, angiosarcoma, cellulitis, mammary Paget disease, telangiectasia, pyoderma, morphea, and trichoepithelioma.⁵ In our patient, the clinical appearance of the lesion resembled a nodular melanoma. Thus, in patients with a history of prostate cancer, it is important to keep cutaneous metastasis in the differential when examining the skin because of the prognostic implications. Cutaneous metastasis of prostate cancer often indicates a poor prognosis.

In a report of 78 patients, the most common sites of skin metastasis for prostate cancer were the inguinal area and penis (28% [22/78]), abdomen (23% [18/78]), head and neck (16% [12/78]), and chest (14% [11/78]); the extremities and back were less frequently involved (10% [8/78] and 9% [7/78], respectively).⁴ Generally, cutaneous metastasis of internal malignancies involves the deep dermis and the subcutaneous tissue. It is common for cutaneous metastases to show histologic features of the primary tumor, as we saw in our patient. In a case series with 45 histologic diagnoses of cutaneous metastases from internal malignancies, 75.5% (34/45) of cases showed morphologic features of the primary tumor.⁶ However, this is not always the case, and the histologic appearance may vary. Metastatic prostate cancer may manifest as sheets, nests, or cords and often may have nuclear pleomorphism with prominent nucleoli.⁷

Immunohistochemical staining can help make a definitive diagnosis and differentiate the source of the tumor. Prostate cancer metastases often will stain positive for NKX3.1, PSA, AMACR, ERG, PSMA, and prosaposin, with PSA being the most specific marker.^7,8 In our patient, no prostate biopsy had been performed, thus the skin biopsy was the diagnostic tissue for the prostatic adenocarcinoma.

Next-generation sequencing showed a TMPRSS2- ERG fusion, which commonly is seen in prostate cancer.⁹ A search of Google Scholar using the terms next-generation sequencing, cutaneous metastasis, and prostate adenocarcinoma yielded 3 additional cases of cutaneous metastasis of prostate cancer in which next-generation sequencing was performed.^10-12 One case showed mutations of the tumor protein 53 (TP53) and phosphatase and tensin homolog (PTEN) genes; one showed just a TP53 mutation; and one showed inactivation of the breast cancer predisposition gene 2 (BRCA2) and amplification of MYC proto-oncogene, BHLH transcription factor (MYC) and fibroblast growth factor receptor 1 (FGFR1).^10,11,12 While limited by a small number of reported cases, there does not appear to be a repeating mutation to suggest a genetic mechanism of skin metastasis.

The route of cutaneous metastasis of prostate cancer still is unclear, but hypothesized mechanisms include hematogenous or lymphatic spread, direct infiltration, or implantation from a surgical scar.¹¹ When cutaneous involvement occurs in an area far from the primary tumor, it is thought to be the result of hematogenous spread, which would be consistent with our patient’s findings.¹³ Given the role of Batson venous plexus as a conduit from the prostate to the vertebral column for metastatic spread and considering the location of the lesion on our patient’s back, we hypothesized that the mechanism of metastasis to the skin was from vascular extension of the metastatic foci involving the vertebrae.

Our case highlights the importance of considering cutaneous involvement of prostatic adenocarcinoma in patients with new skin lesions, particularly in the setting of a known or suspected prostate malignancy. Skin metastasis can have a range of manifestations and provides prognostic information that can help determine the course of treatment.

To the Editor:

Indeterminate cell histiocytosis (ICH) is a rare neoplastic dendritic cell disorder with a poorly understood histogenesis and pathogenesis.¹ The clinical manifestation of ICH is broad and can include isolated or multiple papules or nodules on the face, neck, trunk, arms, or legs. Our case demonstrates a rare occurrence of ICH that initially was misdiagnosed and highlights the use of cobimetinib, a MEK inhibitor, as a potential new therapeutic option for ICH.

A 74-year-old man with a history of type 2 diabetes mellitus presented for evaluation of a progressive pruritic rash of approximately 5 years’ duration. The eruption previously had been diagnosed as Langerhans cell histiocytosis. It started on the chest and spread to the face, neck, trunk, and arms. The patient denied systemic symptoms and had no known history of malignancy.

Physical examination revealed pink to orange smooth papules, nodules, and small plaques on the ears, cheeks, trunk, neck, and arms (Figure 1). Baseline laboratory results showed a normal complete blood count and comprehensive metabolic panel, elevated lactate dehydrogenase and erythrocyte sedimentation rate, and hyperlipidemia. Serology for hepatitis B and C was negative. Bone marrow biopsy was normal, and positron emission tomography/ computed tomography demonstrated no evidence of extracutaneous disease. A punch biopsy of a lesion on the left forearm revealed epithelioid histiocytic proliferation in the dermis extending into the subcutis with a background infiltrate of small lymphocytes. Immunohistochemistry was positive for CD1a and CD56 and was variably positive for CD4 but negative for CD163, CD68, S100, Langerin, cyclin D1, myeloperoxidase, CD21, and CD23. No mutation was detected in BRAF codon 600. Given the negative Langerin stain, these findings were compatible with a diagnosis of ICH. After considering the lack of standard treatment options as well as the recent approval of cobimetinib for histiocytic disorders, we initiated treatment with cobimetinib at the standard dose of 60 mg daily for 21 days followed by a 7-day break.

One month into treatment, the patient’s lesions were less erythematous, and he reported improvement in pruritus. Two months into treatment, there was continued improvement in cutaneous symptoms with flattening of the lesions on the chest and back. At this time, the patient developed edema of the face and ears (Figure 2) and reported weakness, blurred vision, and decreased appetite. He was advised to take an additional 7-day treatment break before resuming cobimetinib at a decreased dose of 40 mg daily. The patient returned to the clinic 1 month later with improved systemic symptoms and continued flattening of the lesions. Five months into treatment, the lesions had continued to improve with complete resolution of the facial plaques (Figure 3).

Indeterminate cell histiocytosis is a rarely diagnosed condition characterized by the proliferation of indeterminate histiocytes that morphologically and immunophenotypically resemble Langerhans cells but lack their characteristic Birbeck granules.² There is no standard treatment for ICH, but previous reports have described improvement with a variety of treatment options including methotrexate,^3,4 UVB phototherapy,⁵ and topical delgocitinib 0.5%.⁶

Because histiocytic disorders are characterized by mutations in the mitogen-activated protein kinase pathway, it is possible that they would be responsive to MEK inhibition. Cobimetinib, a MEK inhibitor initially approved to treat metastatic melanoma, was approved by the US Food and Drug Administration to treat histiocytic disorders in October 2022.⁷ The approval followed the release of data from a phase 2 trial of cobimetinib in 18 adults with various histiocytic disorders, which demonstrated an 89% (16/18) overall response rate with 94% (17/18) of patients remaining progression free at 1 year.⁸ While cobimetinib has not specifically been studied in ICH, given the high response rate in histiocytic disorders and the lack of standard treatment options for ICH, the decision was made to initiate treatment with cobimetinib in our patient. Based on the observed improvement in our patient, we propose cobimetinib as a treatment option for patients with cutaneous ICH and recommend additional studies to confirm its safety and efficacy in patients with this disorder.

To the Editor:

Indeterminate cell histiocytosis (ICH) is a rare neoplastic dendritic cell disorder with a poorly understood histogenesis and pathogenesis.¹ The clinical manifestation of ICH is broad and can include isolated or multiple papules or nodules on the face, neck, trunk, arms, or legs. Our case demonstrates a rare occurrence of ICH that initially was misdiagnosed and highlights the use of cobimetinib, a MEK inhibitor, as a potential new therapeutic option for ICH.

A 74-year-old man with a history of type 2 diabetes mellitus presented for evaluation of a progressive pruritic rash of approximately 5 years’ duration. The eruption previously had been diagnosed as Langerhans cell histiocytosis. It started on the chest and spread to the face, neck, trunk, and arms. The patient denied systemic symptoms and had no known history of malignancy.

Physical examination revealed pink to orange smooth papules, nodules, and small plaques on the ears, cheeks, trunk, neck, and arms (Figure 1). Baseline laboratory results showed a normal complete blood count and comprehensive metabolic panel, elevated lactate dehydrogenase and erythrocyte sedimentation rate, and hyperlipidemia. Serology for hepatitis B and C was negative. Bone marrow biopsy was normal, and positron emission tomography/ computed tomography demonstrated no evidence of extracutaneous disease. A punch biopsy of a lesion on the left forearm revealed epithelioid histiocytic proliferation in the dermis extending into the subcutis with a background infiltrate of small lymphocytes. Immunohistochemistry was positive for CD1a and CD56 and was variably positive for CD4 but negative for CD163, CD68, S100, Langerin, cyclin D1, myeloperoxidase, CD21, and CD23. No mutation was detected in BRAF codon 600. Given the negative Langerin stain, these findings were compatible with a diagnosis of ICH. After considering the lack of standard treatment options as well as the recent approval of cobimetinib for histiocytic disorders, we initiated treatment with cobimetinib at the standard dose of 60 mg daily for 21 days followed by a 7-day break.

One month into treatment, the patient’s lesions were less erythematous, and he reported improvement in pruritus. Two months into treatment, there was continued improvement in cutaneous symptoms with flattening of the lesions on the chest and back. At this time, the patient developed edema of the face and ears (Figure 2) and reported weakness, blurred vision, and decreased appetite. He was advised to take an additional 7-day treatment break before resuming cobimetinib at a decreased dose of 40 mg daily. The patient returned to the clinic 1 month later with improved systemic symptoms and continued flattening of the lesions. Five months into treatment, the lesions had continued to improve with complete resolution of the facial plaques (Figure 3).

Indeterminate cell histiocytosis is a rarely diagnosed condition characterized by the proliferation of indeterminate histiocytes that morphologically and immunophenotypically resemble Langerhans cells but lack their characteristic Birbeck granules.² There is no standard treatment for ICH, but previous reports have described improvement with a variety of treatment options including methotrexate,^3,4 UVB phototherapy,⁵ and topical delgocitinib 0.5%.⁶

Because histiocytic disorders are characterized by mutations in the mitogen-activated protein kinase pathway, it is possible that they would be responsive to MEK inhibition. Cobimetinib, a MEK inhibitor initially approved to treat metastatic melanoma, was approved by the US Food and Drug Administration to treat histiocytic disorders in October 2022.⁷ The approval followed the release of data from a phase 2 trial of cobimetinib in 18 adults with various histiocytic disorders, which demonstrated an 89% (16/18) overall response rate with 94% (17/18) of patients remaining progression free at 1 year.⁸ While cobimetinib has not specifically been studied in ICH, given the high response rate in histiocytic disorders and the lack of standard treatment options for ICH, the decision was made to initiate treatment with cobimetinib in our patient. Based on the observed improvement in our patient, we propose cobimetinib as a treatment option for patients with cutaneous ICH and recommend additional studies to confirm its safety and efficacy in patients with this disorder.

To the Editor:

Indeterminate cell histiocytosis (ICH) is a rare neoplastic dendritic cell disorder with a poorly understood histogenesis and pathogenesis.¹ The clinical manifestation of ICH is broad and can include isolated or multiple papules or nodules on the face, neck, trunk, arms, or legs. Our case demonstrates a rare occurrence of ICH that initially was misdiagnosed and highlights the use of cobimetinib, a MEK inhibitor, as a potential new therapeutic option for ICH.

A 74-year-old man with a history of type 2 diabetes mellitus presented for evaluation of a progressive pruritic rash of approximately 5 years’ duration. The eruption previously had been diagnosed as Langerhans cell histiocytosis. It started on the chest and spread to the face, neck, trunk, and arms. The patient denied systemic symptoms and had no known history of malignancy.

Physical examination revealed pink to orange smooth papules, nodules, and small plaques on the ears, cheeks, trunk, neck, and arms (Figure 1). Baseline laboratory results showed a normal complete blood count and comprehensive metabolic panel, elevated lactate dehydrogenase and erythrocyte sedimentation rate, and hyperlipidemia. Serology for hepatitis B and C was negative. Bone marrow biopsy was normal, and positron emission tomography/ computed tomography demonstrated no evidence of extracutaneous disease. A punch biopsy of a lesion on the left forearm revealed epithelioid histiocytic proliferation in the dermis extending into the subcutis with a background infiltrate of small lymphocytes. Immunohistochemistry was positive for CD1a and CD56 and was variably positive for CD4 but negative for CD163, CD68, S100, Langerin, cyclin D1, myeloperoxidase, CD21, and CD23. No mutation was detected in BRAF codon 600. Given the negative Langerin stain, these findings were compatible with a diagnosis of ICH. After considering the lack of standard treatment options as well as the recent approval of cobimetinib for histiocytic disorders, we initiated treatment with cobimetinib at the standard dose of 60 mg daily for 21 days followed by a 7-day break.

One month into treatment, the patient’s lesions were less erythematous, and he reported improvement in pruritus. Two months into treatment, there was continued improvement in cutaneous symptoms with flattening of the lesions on the chest and back. At this time, the patient developed edema of the face and ears (Figure 2) and reported weakness, blurred vision, and decreased appetite. He was advised to take an additional 7-day treatment break before resuming cobimetinib at a decreased dose of 40 mg daily. The patient returned to the clinic 1 month later with improved systemic symptoms and continued flattening of the lesions. Five months into treatment, the lesions had continued to improve with complete resolution of the facial plaques (Figure 3).

Indeterminate cell histiocytosis is a rarely diagnosed condition characterized by the proliferation of indeterminate histiocytes that morphologically and immunophenotypically resemble Langerhans cells but lack their characteristic Birbeck granules.² There is no standard treatment for ICH, but previous reports have described improvement with a variety of treatment options including methotrexate,^3,4 UVB phototherapy,⁵ and topical delgocitinib 0.5%.⁶

Because histiocytic disorders are characterized by mutations in the mitogen-activated protein kinase pathway, it is possible that they would be responsive to MEK inhibition. Cobimetinib, a MEK inhibitor initially approved to treat metastatic melanoma, was approved by the US Food and Drug Administration to treat histiocytic disorders in October 2022.⁷ The approval followed the release of data from a phase 2 trial of cobimetinib in 18 adults with various histiocytic disorders, which demonstrated an 89% (16/18) overall response rate with 94% (17/18) of patients remaining progression free at 1 year.⁸ While cobimetinib has not specifically been studied in ICH, given the high response rate in histiocytic disorders and the lack of standard treatment options for ICH, the decision was made to initiate treatment with cobimetinib in our patient. Based on the observed improvement in our patient, we propose cobimetinib as a treatment option for patients with cutaneous ICH and recommend additional studies to confirm its safety and efficacy in patients with this disorder.

To the Editor:
Psoriasis is a chronic inflammatory skin condition that commonly affects the nail matrix and/or nail bed.¹ Nail involvement is present in up to 50% of patients with cutaneous psoriasis and 80% of patients with psoriatic arthritis.¹ Approximately 5% to 10% of patients with psoriasis demonstrate isolated nail involvement with no skin or joint manifestations.¹ Nail psoriasis can cause severe pain and psychological distress, and extreme cases may cause considerable morbidity and functional impairment.^2,3 Treatment often requires a long duration and may not result in complete recovery due to the slow rate of nail growth. Patients can progress to permanent nail loss if not treated properly, making early recognition and treatment crucial.^1,2 Despite the availability of various treatment options, many cases remain refractory to standard interventions, which underscores the need for novel therapeutic approaches. Herein, we present a severe case of refractory isolated nail psoriasis that was successfully treated with deucravacitinib, an oral tyrosine kinase 2 (TYK2) inhibitor.

A 59-year-old woman presented with a progressive, yellow, hyperkeratotic lesion on the left thumbnail of 2 years’ duration. The patient noted initial discoloration and peeling at the distal end of the nail. Over time, the discoloration progressed to encompass the entire nail. Previous treatments performed by outside physicians including topical corticosteroids, calcineurin inhibitors, and 2 surgeries to remove the nail plate and nail bed all were unsuccessful. The patient also reported severe left thumbnail pain and pruritus that considerably impaired her ability to work. The rest of the nails were unaffected, and she had no personal or family history of psoriasis. Her medical history was notable for hypertension, gastroesophageal reflux disease, and osteomyelitis of the right thumb without nail involvement. Drug allergies included penicillin G benzathine, sulfonamides, amoxicillin, and ciprofloxacin.

Physical examination of the left thumbnail revealed severe yellow, hyperkeratotic, dystrophic changes with a large, yellow, crumbling hyperkeratotic plaque that extended from approximately 1 cm beyond the nail plate to the proximal end of the distal interphalangeal joint, to and along the lateral nail folds, with extensive distal onycholysis. The proximal and lateral nail folds demonstrated erythema as well as maceration that was extremely tender to minimal palpation (Figure 1). No cutaneous lesions were noted elsewhere on the body. The patient had no tenderness, swelling, or stiffness in any of the joints. The differential diagnosis at the time included squamous cell carcinoma of the nail bed and acrodermatitis continua of Hallopeau.

Radiography of the left thumb revealed irregular swelling and nonspecific soft tissue enlargement at the tip of the digit. A nail clipping from the left thumbnail and 3-mm punch biopsies of the lateral and proximal nail folds as well as the horn of the proximal nail fold (Figure 2) were negative for fungus and confirmed psoriasiform dermatitis of the nail.

The patient was started on vinegar soaks (1:1 ratio of vinegar to water) every other day as well as urea cream 10%, ammonium lactate 15%, and petrolatum twice daily for 2 months without considerable improvement. Due to lack of improvement during this 2-month period, the patient subsequently was started on oral deucravacitinib 6 mg/d along with continued use of petrolatum twice daily and vinegar soaks every other day. We selected a trial of deucravacitinib for our patient because of its convenient daily oral dosing and promising clinical evidence.^4,5 After 2 months of treatment with deucravacitinib, the patient reported substantial improvement and satisfaction with the treatment results. Physical examination of the left thumbnail after 2 months of deucravacitinib treatment revealed mildly hyperkeratotic, yellow, dystrophic changes of the nail with notable improvement of the yellow hyperkeratotic plaque on the distal thumbnail. Normal-appearing nail growth was noted at the proximal nail fold, demonstrating considerable improvement from the initial presentation (Figure 3). However, the patient had developed multiple oral ulcers, generalized pruritus, and an annular urticarial plaque on the left arm. As such, deucravacitinib was discontinued after 2 months of treatment. These symptoms resolved within a week of discontinuing deucravacitinib.

While the etiology of nail psoriasis remains unclear, it is believed to be due to a combination of immunologic, genetic, and environmental factors.³ Classical clinical features include nail pitting, leukonychia, onycholysis, nail bed hyperkeratosis, and splinter hemorrhages.^1,3 Our patient exhibited a severe form of nail psoriasis, encompassing the entire nail matrix and bed and extending to the distal interphalangeal joint and lateral nail folds. Previous surgical interventions may have triggered the Koebner phenomenon—which commonly is associated with psoriasis—and resulted in new skin lesions as a secondary response to the surgical trauma.⁶ The severity of the condition profoundly impacted her quality of life and considerably hindered her ability to work.

Treatment for nail psoriasis includes topical or systemic therapies such as corticosteroids, vitamin D analogs, tacrolimus, and tumor necrosis factor α inhibitors.^1,3 Topical treatment is challenging because it is difficult to deliver medication effectively to the nail bed and nail matrix, and patient adherence may be poor.² Although it has been shown to be effective, intralesional triamcinolone can be associated with pain as the most common adverse effect.⁷ Systemic medications such as oral methotrexate also may be effective but are contraindicated in pregnant patients and are associated with potential adverse events (AEs), including hepatotoxicity and acute kidney injury.⁸ The use of biologics may be challenging due to potential AEs and patient reluctance toward injection-based treatments.⁹

Deucravacitinib is a TYK2 inhibitor approved for treatment of plaque psoriasis.¹⁰ Tyrosine kinase 2 is an intracellular kinase that mediates the signaling of IL-23 and other cytokines involved in psoriasis pathogenesis.¹⁰ Deucravacitinib selectively binds to the regulatory domain of TYK2, leading to targeted allosteric inhibition of TYK2-mediated IL-23 and type I interferon signaling.^4,5,10 Compared with biologics, deucravacitinib is advantageous because it can be administered as a daily oral pill, encouraging high patient compliance.

In the POETYK PSO-1 and PSO-2 phase 3 randomized controlled trials, 20.9% (n=332) and 20.3% (n=510) of deucravacitinib-treated patients with moderate to severe nail involvement achieved a Physician’s Global Assessment of Fingernail score of 0/1 compared with 8.8% (n=165) and 7.9% (n=254) of patients in the placebo group, respectively. All patients in these trials had a diagnosis of plaque psoriasis with at least 10% body surface area involvement; none of the patients had isolated nail psoriasis.^4,5

The phase 3 POETYK PSO-1 and PSO-2 trials demonstrated deucravacitinib to be safe and well tolerated with minimal AEs.^4,5 However, the development of AEs in our patient, including oral ulcers and generalized pruritus, underscores the need for close monitoring and consideration of potential risks of treatment. Common AEs associated with deucravacitinib include upper respiratory infections (19.2% [n=840]), increased blood creatine phosphokinase levels (2.7% [n=840]), herpes simplex virus (2.0% [n=840]), and mouth ulcers (1.9% [n=840]).¹¹

Patient education also is a crucial component in the treatment of nail psoriasis. Physicians should emphasize the slow growth of nails and need for prolonged treatment. Clear communication and realistic expectations are essential for ensuring patient adherence to treatment.

Our case highlights the potential efficacy and safety of deucravacitinib for treatment of nail psoriasis, potentially laying the groundwork for future clinical studies. Our patient had a severe case of nail psoriasis that involved the entire nail bed and nail plate, resulting in extreme pain, pruritus, and functional impairment. Her case was unique because involvement was isolated to the nail without any accompanying skin or joint manifestations. She showed a favorable response to deucravacitinib within only 2 months of treatment and exhibited considerable improvement of nail psoriasis, with a reported high level of satisfaction with the treatment. We plan to continue to monitor the patient for long-term results. Future randomized clinical trials with longer follow-up periods are crucial to further establish the efficacy and safety of deucravacitinib for treatment of nail psoriasis.

To the Editor:
Psoriasis is a chronic inflammatory skin condition that commonly affects the nail matrix and/or nail bed.¹ Nail involvement is present in up to 50% of patients with cutaneous psoriasis and 80% of patients with psoriatic arthritis.¹ Approximately 5% to 10% of patients with psoriasis demonstrate isolated nail involvement with no skin or joint manifestations.¹ Nail psoriasis can cause severe pain and psychological distress, and extreme cases may cause considerable morbidity and functional impairment.^2,3 Treatment often requires a long duration and may not result in complete recovery due to the slow rate of nail growth. Patients can progress to permanent nail loss if not treated properly, making early recognition and treatment crucial.^1,2 Despite the availability of various treatment options, many cases remain refractory to standard interventions, which underscores the need for novel therapeutic approaches. Herein, we present a severe case of refractory isolated nail psoriasis that was successfully treated with deucravacitinib, an oral tyrosine kinase 2 (TYK2) inhibitor.

A 59-year-old woman presented with a progressive, yellow, hyperkeratotic lesion on the left thumbnail of 2 years’ duration. The patient noted initial discoloration and peeling at the distal end of the nail. Over time, the discoloration progressed to encompass the entire nail. Previous treatments performed by outside physicians including topical corticosteroids, calcineurin inhibitors, and 2 surgeries to remove the nail plate and nail bed all were unsuccessful. The patient also reported severe left thumbnail pain and pruritus that considerably impaired her ability to work. The rest of the nails were unaffected, and she had no personal or family history of psoriasis. Her medical history was notable for hypertension, gastroesophageal reflux disease, and osteomyelitis of the right thumb without nail involvement. Drug allergies included penicillin G benzathine, sulfonamides, amoxicillin, and ciprofloxacin.

Physical examination of the left thumbnail revealed severe yellow, hyperkeratotic, dystrophic changes with a large, yellow, crumbling hyperkeratotic plaque that extended from approximately 1 cm beyond the nail plate to the proximal end of the distal interphalangeal joint, to and along the lateral nail folds, with extensive distal onycholysis. The proximal and lateral nail folds demonstrated erythema as well as maceration that was extremely tender to minimal palpation (Figure 1). No cutaneous lesions were noted elsewhere on the body. The patient had no tenderness, swelling, or stiffness in any of the joints. The differential diagnosis at the time included squamous cell carcinoma of the nail bed and acrodermatitis continua of Hallopeau.

Radiography of the left thumb revealed irregular swelling and nonspecific soft tissue enlargement at the tip of the digit. A nail clipping from the left thumbnail and 3-mm punch biopsies of the lateral and proximal nail folds as well as the horn of the proximal nail fold (Figure 2) were negative for fungus and confirmed psoriasiform dermatitis of the nail.

The patient was started on vinegar soaks (1:1 ratio of vinegar to water) every other day as well as urea cream 10%, ammonium lactate 15%, and petrolatum twice daily for 2 months without considerable improvement. Due to lack of improvement during this 2-month period, the patient subsequently was started on oral deucravacitinib 6 mg/d along with continued use of petrolatum twice daily and vinegar soaks every other day. We selected a trial of deucravacitinib for our patient because of its convenient daily oral dosing and promising clinical evidence.^4,5 After 2 months of treatment with deucravacitinib, the patient reported substantial improvement and satisfaction with the treatment results. Physical examination of the left thumbnail after 2 months of deucravacitinib treatment revealed mildly hyperkeratotic, yellow, dystrophic changes of the nail with notable improvement of the yellow hyperkeratotic plaque on the distal thumbnail. Normal-appearing nail growth was noted at the proximal nail fold, demonstrating considerable improvement from the initial presentation (Figure 3). However, the patient had developed multiple oral ulcers, generalized pruritus, and an annular urticarial plaque on the left arm. As such, deucravacitinib was discontinued after 2 months of treatment. These symptoms resolved within a week of discontinuing deucravacitinib.

While the etiology of nail psoriasis remains unclear, it is believed to be due to a combination of immunologic, genetic, and environmental factors.³ Classical clinical features include nail pitting, leukonychia, onycholysis, nail bed hyperkeratosis, and splinter hemorrhages.^1,3 Our patient exhibited a severe form of nail psoriasis, encompassing the entire nail matrix and bed and extending to the distal interphalangeal joint and lateral nail folds. Previous surgical interventions may have triggered the Koebner phenomenon—which commonly is associated with psoriasis—and resulted in new skin lesions as a secondary response to the surgical trauma.⁶ The severity of the condition profoundly impacted her quality of life and considerably hindered her ability to work.

Treatment for nail psoriasis includes topical or systemic therapies such as corticosteroids, vitamin D analogs, tacrolimus, and tumor necrosis factor α inhibitors.^1,3 Topical treatment is challenging because it is difficult to deliver medication effectively to the nail bed and nail matrix, and patient adherence may be poor.² Although it has been shown to be effective, intralesional triamcinolone can be associated with pain as the most common adverse effect.⁷ Systemic medications such as oral methotrexate also may be effective but are contraindicated in pregnant patients and are associated with potential adverse events (AEs), including hepatotoxicity and acute kidney injury.⁸ The use of biologics may be challenging due to potential AEs and patient reluctance toward injection-based treatments.⁹

Deucravacitinib is a TYK2 inhibitor approved for treatment of plaque psoriasis.¹⁰ Tyrosine kinase 2 is an intracellular kinase that mediates the signaling of IL-23 and other cytokines involved in psoriasis pathogenesis.¹⁰ Deucravacitinib selectively binds to the regulatory domain of TYK2, leading to targeted allosteric inhibition of TYK2-mediated IL-23 and type I interferon signaling.^4,5,10 Compared with biologics, deucravacitinib is advantageous because it can be administered as a daily oral pill, encouraging high patient compliance.

In the POETYK PSO-1 and PSO-2 phase 3 randomized controlled trials, 20.9% (n=332) and 20.3% (n=510) of deucravacitinib-treated patients with moderate to severe nail involvement achieved a Physician’s Global Assessment of Fingernail score of 0/1 compared with 8.8% (n=165) and 7.9% (n=254) of patients in the placebo group, respectively. All patients in these trials had a diagnosis of plaque psoriasis with at least 10% body surface area involvement; none of the patients had isolated nail psoriasis.^4,5

The phase 3 POETYK PSO-1 and PSO-2 trials demonstrated deucravacitinib to be safe and well tolerated with minimal AEs.^4,5 However, the development of AEs in our patient, including oral ulcers and generalized pruritus, underscores the need for close monitoring and consideration of potential risks of treatment. Common AEs associated with deucravacitinib include upper respiratory infections (19.2% [n=840]), increased blood creatine phosphokinase levels (2.7% [n=840]), herpes simplex virus (2.0% [n=840]), and mouth ulcers (1.9% [n=840]).¹¹

Patient education also is a crucial component in the treatment of nail psoriasis. Physicians should emphasize the slow growth of nails and need for prolonged treatment. Clear communication and realistic expectations are essential for ensuring patient adherence to treatment.

Our case highlights the potential efficacy and safety of deucravacitinib for treatment of nail psoriasis, potentially laying the groundwork for future clinical studies. Our patient had a severe case of nail psoriasis that involved the entire nail bed and nail plate, resulting in extreme pain, pruritus, and functional impairment. Her case was unique because involvement was isolated to the nail without any accompanying skin or joint manifestations. She showed a favorable response to deucravacitinib within only 2 months of treatment and exhibited considerable improvement of nail psoriasis, with a reported high level of satisfaction with the treatment. We plan to continue to monitor the patient for long-term results. Future randomized clinical trials with longer follow-up periods are crucial to further establish the efficacy and safety of deucravacitinib for treatment of nail psoriasis.

To the Editor:
Psoriasis is a chronic inflammatory skin condition that commonly affects the nail matrix and/or nail bed.¹ Nail involvement is present in up to 50% of patients with cutaneous psoriasis and 80% of patients with psoriatic arthritis.¹ Approximately 5% to 10% of patients with psoriasis demonstrate isolated nail involvement with no skin or joint manifestations.¹ Nail psoriasis can cause severe pain and psychological distress, and extreme cases may cause considerable morbidity and functional impairment.^2,3 Treatment often requires a long duration and may not result in complete recovery due to the slow rate of nail growth. Patients can progress to permanent nail loss if not treated properly, making early recognition and treatment crucial.^1,2 Despite the availability of various treatment options, many cases remain refractory to standard interventions, which underscores the need for novel therapeutic approaches. Herein, we present a severe case of refractory isolated nail psoriasis that was successfully treated with deucravacitinib, an oral tyrosine kinase 2 (TYK2) inhibitor.

A 59-year-old woman presented with a progressive, yellow, hyperkeratotic lesion on the left thumbnail of 2 years’ duration. The patient noted initial discoloration and peeling at the distal end of the nail. Over time, the discoloration progressed to encompass the entire nail. Previous treatments performed by outside physicians including topical corticosteroids, calcineurin inhibitors, and 2 surgeries to remove the nail plate and nail bed all were unsuccessful. The patient also reported severe left thumbnail pain and pruritus that considerably impaired her ability to work. The rest of the nails were unaffected, and she had no personal or family history of psoriasis. Her medical history was notable for hypertension, gastroesophageal reflux disease, and osteomyelitis of the right thumb without nail involvement. Drug allergies included penicillin G benzathine, sulfonamides, amoxicillin, and ciprofloxacin.

Physical examination of the left thumbnail revealed severe yellow, hyperkeratotic, dystrophic changes with a large, yellow, crumbling hyperkeratotic plaque that extended from approximately 1 cm beyond the nail plate to the proximal end of the distal interphalangeal joint, to and along the lateral nail folds, with extensive distal onycholysis. The proximal and lateral nail folds demonstrated erythema as well as maceration that was extremely tender to minimal palpation (Figure 1). No cutaneous lesions were noted elsewhere on the body. The patient had no tenderness, swelling, or stiffness in any of the joints. The differential diagnosis at the time included squamous cell carcinoma of the nail bed and acrodermatitis continua of Hallopeau.

Radiography of the left thumb revealed irregular swelling and nonspecific soft tissue enlargement at the tip of the digit. A nail clipping from the left thumbnail and 3-mm punch biopsies of the lateral and proximal nail folds as well as the horn of the proximal nail fold (Figure 2) were negative for fungus and confirmed psoriasiform dermatitis of the nail.

The patient was started on vinegar soaks (1:1 ratio of vinegar to water) every other day as well as urea cream 10%, ammonium lactate 15%, and petrolatum twice daily for 2 months without considerable improvement. Due to lack of improvement during this 2-month period, the patient subsequently was started on oral deucravacitinib 6 mg/d along with continued use of petrolatum twice daily and vinegar soaks every other day. We selected a trial of deucravacitinib for our patient because of its convenient daily oral dosing and promising clinical evidence.^4,5 After 2 months of treatment with deucravacitinib, the patient reported substantial improvement and satisfaction with the treatment results. Physical examination of the left thumbnail after 2 months of deucravacitinib treatment revealed mildly hyperkeratotic, yellow, dystrophic changes of the nail with notable improvement of the yellow hyperkeratotic plaque on the distal thumbnail. Normal-appearing nail growth was noted at the proximal nail fold, demonstrating considerable improvement from the initial presentation (Figure 3). However, the patient had developed multiple oral ulcers, generalized pruritus, and an annular urticarial plaque on the left arm. As such, deucravacitinib was discontinued after 2 months of treatment. These symptoms resolved within a week of discontinuing deucravacitinib.

While the etiology of nail psoriasis remains unclear, it is believed to be due to a combination of immunologic, genetic, and environmental factors.³ Classical clinical features include nail pitting, leukonychia, onycholysis, nail bed hyperkeratosis, and splinter hemorrhages.^1,3 Our patient exhibited a severe form of nail psoriasis, encompassing the entire nail matrix and bed and extending to the distal interphalangeal joint and lateral nail folds. Previous surgical interventions may have triggered the Koebner phenomenon—which commonly is associated with psoriasis—and resulted in new skin lesions as a secondary response to the surgical trauma.⁶ The severity of the condition profoundly impacted her quality of life and considerably hindered her ability to work.

Treatment for nail psoriasis includes topical or systemic therapies such as corticosteroids, vitamin D analogs, tacrolimus, and tumor necrosis factor α inhibitors.^1,3 Topical treatment is challenging because it is difficult to deliver medication effectively to the nail bed and nail matrix, and patient adherence may be poor.² Although it has been shown to be effective, intralesional triamcinolone can be associated with pain as the most common adverse effect.⁷ Systemic medications such as oral methotrexate also may be effective but are contraindicated in pregnant patients and are associated with potential adverse events (AEs), including hepatotoxicity and acute kidney injury.⁸ The use of biologics may be challenging due to potential AEs and patient reluctance toward injection-based treatments.⁹

Deucravacitinib is a TYK2 inhibitor approved for treatment of plaque psoriasis.¹⁰ Tyrosine kinase 2 is an intracellular kinase that mediates the signaling of IL-23 and other cytokines involved in psoriasis pathogenesis.¹⁰ Deucravacitinib selectively binds to the regulatory domain of TYK2, leading to targeted allosteric inhibition of TYK2-mediated IL-23 and type I interferon signaling.^4,5,10 Compared with biologics, deucravacitinib is advantageous because it can be administered as a daily oral pill, encouraging high patient compliance.

In the POETYK PSO-1 and PSO-2 phase 3 randomized controlled trials, 20.9% (n=332) and 20.3% (n=510) of deucravacitinib-treated patients with moderate to severe nail involvement achieved a Physician’s Global Assessment of Fingernail score of 0/1 compared with 8.8% (n=165) and 7.9% (n=254) of patients in the placebo group, respectively. All patients in these trials had a diagnosis of plaque psoriasis with at least 10% body surface area involvement; none of the patients had isolated nail psoriasis.^4,5

The phase 3 POETYK PSO-1 and PSO-2 trials demonstrated deucravacitinib to be safe and well tolerated with minimal AEs.^4,5 However, the development of AEs in our patient, including oral ulcers and generalized pruritus, underscores the need for close monitoring and consideration of potential risks of treatment. Common AEs associated with deucravacitinib include upper respiratory infections (19.2% [n=840]), increased blood creatine phosphokinase levels (2.7% [n=840]), herpes simplex virus (2.0% [n=840]), and mouth ulcers (1.9% [n=840]).¹¹

Patient education also is a crucial component in the treatment of nail psoriasis. Physicians should emphasize the slow growth of nails and need for prolonged treatment. Clear communication and realistic expectations are essential for ensuring patient adherence to treatment.

Our case highlights the potential efficacy and safety of deucravacitinib for treatment of nail psoriasis, potentially laying the groundwork for future clinical studies. Our patient had a severe case of nail psoriasis that involved the entire nail bed and nail plate, resulting in extreme pain, pruritus, and functional impairment. Her case was unique because involvement was isolated to the nail without any accompanying skin or joint manifestations. She showed a favorable response to deucravacitinib within only 2 months of treatment and exhibited considerable improvement of nail psoriasis, with a reported high level of satisfaction with the treatment. We plan to continue to monitor the patient for long-term results. Future randomized clinical trials with longer follow-up periods are crucial to further establish the efficacy and safety of deucravacitinib for treatment of nail psoriasis.