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A 67-year-old woman has had a very itchy rash on the dorsa of both feet for almost a year. In addition to consulting her primary care provider, she has presented to a number of medical venues, including urgent care clinics. Different products have been prescribed—including clotrimazole cream, nystatin powder, and OTC hydrocortisone 1% cream—none of which produced any beneficial effect. So the patient finally self-refers to dermatology.
She reports that at one point, she was convinced her shoes were the source of the problem. But trying new shoes and even going entirely barefoot during a two-week vacation at the beach made no difference.
The patient admits that it is “impossible” to leave the lesions alone, because they are so itchy. She knows that “scratching can’t be good,” so she tries to just rub them, often with a wet washcloth.
Aside from the foot rash, her health is excellent. Her only medications are NSAIDs for mild arthritis.
EXAMINATION
The lesions are confined to the forefeet. There are about five on the right foot and three on the left. The lesions are dark purplish round plaques with planar surfaces that are shiny but have a white frosting-like finish. On average, they measure 1.8 cm in diameter. No surrounding inflammation is appreciated. The patient has otherwise unremarkable type IV skin.
What is the diagnosis?
DIAGNOSIS
Punch biopsy confirms the expected diagnosis of lichen planus.
DISCUSSION
Lichen planus (LP) is a very common problem seen in dermatology offices worldwide. LP represents an immune response of unknown origin and may be found in association with other diseases of altered immunity (eg, dermatomyositis, alopecia areata, vitiligo, morphea, and myasthenia gravis). Some studies support the theory that LP is caused by hepatitis C.
The most common forms of LP lend themselves to a useful mnemonic device that uses the letter “P” to describe common features of the disease: purple, papular or plaquish, planar (flat) surfaces, polygonal shapes, pruritic, penile (frequent location), and finally, “puzzling” to the clinician.
In contrast to this particular case, LP commonly affects flexural surfaces, such as the volar wrist. LP can also affect nails (with dystrophy or onycholysis), the scalp, and, most notoriously, the oral mucosae, where it can cause ulcerations and intense burning. Oral lesions often present with a lacy white look on the buccal mucosal surfaces.
LP is only one of a number of skin diseases that “koebnerize” (ie, form along lines of trauma, such as a scratch). The resulting linear collection of planar purple papules—known as the Koebner phenomenon—is useful for diagnosis.
Biopsy is often needed to confirm the diagnosis. It will show hyperkeratotic epidermis with irregular acanthosis. In the upper dermis, there is often an infiltrating band of lymphocytic and histiocytic cells, along with many Langerhans cells, that effectively obliterates the dermo-epidermal junction (a pathognomic finding of LP).
Most cases of LP eventually resolve, usually within months, though some can persist for years. Treatment can be problematic, especially when the disease is widespread or manifests in difficult areas, such as the mouth or scalp. This particular patient’s problem was relatively simple to treat with topical clobetasol cream under occlusion (bid for three weeks). Had that not worked, we could have tried intralesional injection of triamcinolone (10 mg per cc).
This case was typical of LP seen on the legs of older patients with darker skin. In these patients, the lesions tend to become hypertrophic and darker than the usual light pink to purple seen in those with fairer skin.
The differential for LP includes psoriasis, fixed-drug eruption, granuloma annulare, and nummular eczema.
TAKE-HOME LEARNING POINTS
• Lichen planus (LP) is a commonly encountered inflammatory condition that classically affects flexural skin, such as the volar wrist.
• LP lesions can often be seen in a linear configuration, following the line of a scratch or other trauma, a phenomenon known as the Koebner phenomenon (the isomorphic linear response), which can be helpful diagnostically.
• The “Ps” of LP include papular, purple, planar, plaquish, pruritic, penile, polygonal, and puzzling.
• LP can also affect hair follicles, nails, and oral mucosa.
• LP can present with hypertrophic plaques, especially on legs and feet.
A 67-year-old woman has had a very itchy rash on the dorsa of both feet for almost a year. In addition to consulting her primary care provider, she has presented to a number of medical venues, including urgent care clinics. Different products have been prescribed—including clotrimazole cream, nystatin powder, and OTC hydrocortisone 1% cream—none of which produced any beneficial effect. So the patient finally self-refers to dermatology.
She reports that at one point, she was convinced her shoes were the source of the problem. But trying new shoes and even going entirely barefoot during a two-week vacation at the beach made no difference.
The patient admits that it is “impossible” to leave the lesions alone, because they are so itchy. She knows that “scratching can’t be good,” so she tries to just rub them, often with a wet washcloth.
Aside from the foot rash, her health is excellent. Her only medications are NSAIDs for mild arthritis.
EXAMINATION
The lesions are confined to the forefeet. There are about five on the right foot and three on the left. The lesions are dark purplish round plaques with planar surfaces that are shiny but have a white frosting-like finish. On average, they measure 1.8 cm in diameter. No surrounding inflammation is appreciated. The patient has otherwise unremarkable type IV skin.
What is the diagnosis?
DIAGNOSIS
Punch biopsy confirms the expected diagnosis of lichen planus.
DISCUSSION
Lichen planus (LP) is a very common problem seen in dermatology offices worldwide. LP represents an immune response of unknown origin and may be found in association with other diseases of altered immunity (eg, dermatomyositis, alopecia areata, vitiligo, morphea, and myasthenia gravis). Some studies support the theory that LP is caused by hepatitis C.
The most common forms of LP lend themselves to a useful mnemonic device that uses the letter “P” to describe common features of the disease: purple, papular or plaquish, planar (flat) surfaces, polygonal shapes, pruritic, penile (frequent location), and finally, “puzzling” to the clinician.
In contrast to this particular case, LP commonly affects flexural surfaces, such as the volar wrist. LP can also affect nails (with dystrophy or onycholysis), the scalp, and, most notoriously, the oral mucosae, where it can cause ulcerations and intense burning. Oral lesions often present with a lacy white look on the buccal mucosal surfaces.
LP is only one of a number of skin diseases that “koebnerize” (ie, form along lines of trauma, such as a scratch). The resulting linear collection of planar purple papules—known as the Koebner phenomenon—is useful for diagnosis.
Biopsy is often needed to confirm the diagnosis. It will show hyperkeratotic epidermis with irregular acanthosis. In the upper dermis, there is often an infiltrating band of lymphocytic and histiocytic cells, along with many Langerhans cells, that effectively obliterates the dermo-epidermal junction (a pathognomic finding of LP).
Most cases of LP eventually resolve, usually within months, though some can persist for years. Treatment can be problematic, especially when the disease is widespread or manifests in difficult areas, such as the mouth or scalp. This particular patient’s problem was relatively simple to treat with topical clobetasol cream under occlusion (bid for three weeks). Had that not worked, we could have tried intralesional injection of triamcinolone (10 mg per cc).
This case was typical of LP seen on the legs of older patients with darker skin. In these patients, the lesions tend to become hypertrophic and darker than the usual light pink to purple seen in those with fairer skin.
The differential for LP includes psoriasis, fixed-drug eruption, granuloma annulare, and nummular eczema.
TAKE-HOME LEARNING POINTS
• Lichen planus (LP) is a commonly encountered inflammatory condition that classically affects flexural skin, such as the volar wrist.
• LP lesions can often be seen in a linear configuration, following the line of a scratch or other trauma, a phenomenon known as the Koebner phenomenon (the isomorphic linear response), which can be helpful diagnostically.
• The “Ps” of LP include papular, purple, planar, plaquish, pruritic, penile, polygonal, and puzzling.
• LP can also affect hair follicles, nails, and oral mucosa.
• LP can present with hypertrophic plaques, especially on legs and feet.
A 67-year-old woman has had a very itchy rash on the dorsa of both feet for almost a year. In addition to consulting her primary care provider, she has presented to a number of medical venues, including urgent care clinics. Different products have been prescribed—including clotrimazole cream, nystatin powder, and OTC hydrocortisone 1% cream—none of which produced any beneficial effect. So the patient finally self-refers to dermatology.
She reports that at one point, she was convinced her shoes were the source of the problem. But trying new shoes and even going entirely barefoot during a two-week vacation at the beach made no difference.
The patient admits that it is “impossible” to leave the lesions alone, because they are so itchy. She knows that “scratching can’t be good,” so she tries to just rub them, often with a wet washcloth.
Aside from the foot rash, her health is excellent. Her only medications are NSAIDs for mild arthritis.
EXAMINATION
The lesions are confined to the forefeet. There are about five on the right foot and three on the left. The lesions are dark purplish round plaques with planar surfaces that are shiny but have a white frosting-like finish. On average, they measure 1.8 cm in diameter. No surrounding inflammation is appreciated. The patient has otherwise unremarkable type IV skin.
What is the diagnosis?
DIAGNOSIS
Punch biopsy confirms the expected diagnosis of lichen planus.
DISCUSSION
Lichen planus (LP) is a very common problem seen in dermatology offices worldwide. LP represents an immune response of unknown origin and may be found in association with other diseases of altered immunity (eg, dermatomyositis, alopecia areata, vitiligo, morphea, and myasthenia gravis). Some studies support the theory that LP is caused by hepatitis C.
The most common forms of LP lend themselves to a useful mnemonic device that uses the letter “P” to describe common features of the disease: purple, papular or plaquish, planar (flat) surfaces, polygonal shapes, pruritic, penile (frequent location), and finally, “puzzling” to the clinician.
In contrast to this particular case, LP commonly affects flexural surfaces, such as the volar wrist. LP can also affect nails (with dystrophy or onycholysis), the scalp, and, most notoriously, the oral mucosae, where it can cause ulcerations and intense burning. Oral lesions often present with a lacy white look on the buccal mucosal surfaces.
LP is only one of a number of skin diseases that “koebnerize” (ie, form along lines of trauma, such as a scratch). The resulting linear collection of planar purple papules—known as the Koebner phenomenon—is useful for diagnosis.
Biopsy is often needed to confirm the diagnosis. It will show hyperkeratotic epidermis with irregular acanthosis. In the upper dermis, there is often an infiltrating band of lymphocytic and histiocytic cells, along with many Langerhans cells, that effectively obliterates the dermo-epidermal junction (a pathognomic finding of LP).
Most cases of LP eventually resolve, usually within months, though some can persist for years. Treatment can be problematic, especially when the disease is widespread or manifests in difficult areas, such as the mouth or scalp. This particular patient’s problem was relatively simple to treat with topical clobetasol cream under occlusion (bid for three weeks). Had that not worked, we could have tried intralesional injection of triamcinolone (10 mg per cc).
This case was typical of LP seen on the legs of older patients with darker skin. In these patients, the lesions tend to become hypertrophic and darker than the usual light pink to purple seen in those with fairer skin.
The differential for LP includes psoriasis, fixed-drug eruption, granuloma annulare, and nummular eczema.
TAKE-HOME LEARNING POINTS
• Lichen planus (LP) is a commonly encountered inflammatory condition that classically affects flexural skin, such as the volar wrist.
• LP lesions can often be seen in a linear configuration, following the line of a scratch or other trauma, a phenomenon known as the Koebner phenomenon (the isomorphic linear response), which can be helpful diagnostically.
• The “Ps” of LP include papular, purple, planar, plaquish, pruritic, penile, polygonal, and puzzling.
• LP can also affect hair follicles, nails, and oral mucosa.
• LP can present with hypertrophic plaques, especially on legs and feet.
