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A 55-year-old woman presents for evaluation of a widespread rash that first appeared several months ago. The rash has resisted treatment with various OTC products—antifungal cream (tolnaftate), triple-antibiotic cream, and tea tree oil—and continues to itch terribly at times.
Her primary care provider prescribed oral terbinafine (250 mg/d) for a proposed fungal etiology after viewing the rash with a Wood lamp and performing a KOH prep. A one-month course yielded no relief.
The patient claims to be in good health otherwise. She does admit to going through a stressful period involving job loss, divorce, and care of her aging parents.
EXAMINATION
Multiple papulosquamous papules, nodules, and plaques are located on the patient’s arms, legs, wrists, and sacrum. The lesions range from pinpoint to several centimeters and oval to polygonal. They have a striking purple appearance. On closer inspection, many have a shiny, whitish sheen on the surface.
What is the diagnosis?
This is a classic case of lichen planus (LP), an unusual papulosquamous condition of unknown etiology. In addition to the mentioned areas, it can affect the mucosal surfaces, scalp, genitals, nails, and internal organs.
There is no evidence that the cause is infectious; rather, it appears to be triggered by a reaction to an unknown (possibly autoimmune) antigen. LP targets specific cells and produces a lichenoid reaction, in which the upper level of the dermis is broken down by an apoptotic process. This produces a characteristic sawtooth pattern at the dermoepidermal junction by a pathognomic lymphocytic infiltrate. The surface of the affected skin has a shiny, frosty appearance, also seen in other lichenoid conditions (eg, lichen sclerosus et atrophicus).
Other key diagnostic features are classified as “the Ps”: purple, plaquish, papular, planar (flat-topped), polygonal (multi-angular), penile, pruritic, and puzzling. The last word is key to triggering consideration of the other “Ps.”
LP that affects the scalp and mucosal surfaces can be problematic to treat. Topical steroids are the mainstay, but treatment can also include oral retinoids (acetretin, isotretinoin), methotrexate, antimalarials, and cyclosporine. Furthermore, LP can overlap with other diseases—notably lupus, for which TNF-[a] inhibitors are used with some success. For limited disease, intralesional steroid injections can be used (5 to 10 mg/cc triamcinolone).
This patient achieved good relief with a combination of topical and intralesional steroids. Fortunately, in most cases, the disease eventually resolves on its own.
TAKE-HOME LEARNING POINTS
- Lichen planus is an unusual condition, but the look and distribution seen in this case are fairly typical.
- The classic diagnostic “Ps” include: purple, papular, pruritic, plaquish, planar, and most of all puzzling.
- Wood lamp examination is useless for the most common dermatophytoses, which will not fluoresce; however, KOH preps are useful when correctly interpreted.
- In more obscure cases, a punch or shave biopsy will confirm the diagnosis.
A 55-year-old woman presents for evaluation of a widespread rash that first appeared several months ago. The rash has resisted treatment with various OTC products—antifungal cream (tolnaftate), triple-antibiotic cream, and tea tree oil—and continues to itch terribly at times.
Her primary care provider prescribed oral terbinafine (250 mg/d) for a proposed fungal etiology after viewing the rash with a Wood lamp and performing a KOH prep. A one-month course yielded no relief.
The patient claims to be in good health otherwise. She does admit to going through a stressful period involving job loss, divorce, and care of her aging parents.
EXAMINATION
Multiple papulosquamous papules, nodules, and plaques are located on the patient’s arms, legs, wrists, and sacrum. The lesions range from pinpoint to several centimeters and oval to polygonal. They have a striking purple appearance. On closer inspection, many have a shiny, whitish sheen on the surface.
What is the diagnosis?
This is a classic case of lichen planus (LP), an unusual papulosquamous condition of unknown etiology. In addition to the mentioned areas, it can affect the mucosal surfaces, scalp, genitals, nails, and internal organs.
There is no evidence that the cause is infectious; rather, it appears to be triggered by a reaction to an unknown (possibly autoimmune) antigen. LP targets specific cells and produces a lichenoid reaction, in which the upper level of the dermis is broken down by an apoptotic process. This produces a characteristic sawtooth pattern at the dermoepidermal junction by a pathognomic lymphocytic infiltrate. The surface of the affected skin has a shiny, frosty appearance, also seen in other lichenoid conditions (eg, lichen sclerosus et atrophicus).
Other key diagnostic features are classified as “the Ps”: purple, plaquish, papular, planar (flat-topped), polygonal (multi-angular), penile, pruritic, and puzzling. The last word is key to triggering consideration of the other “Ps.”
LP that affects the scalp and mucosal surfaces can be problematic to treat. Topical steroids are the mainstay, but treatment can also include oral retinoids (acetretin, isotretinoin), methotrexate, antimalarials, and cyclosporine. Furthermore, LP can overlap with other diseases—notably lupus, for which TNF-[a] inhibitors are used with some success. For limited disease, intralesional steroid injections can be used (5 to 10 mg/cc triamcinolone).
This patient achieved good relief with a combination of topical and intralesional steroids. Fortunately, in most cases, the disease eventually resolves on its own.
TAKE-HOME LEARNING POINTS
- Lichen planus is an unusual condition, but the look and distribution seen in this case are fairly typical.
- The classic diagnostic “Ps” include: purple, papular, pruritic, plaquish, planar, and most of all puzzling.
- Wood lamp examination is useless for the most common dermatophytoses, which will not fluoresce; however, KOH preps are useful when correctly interpreted.
- In more obscure cases, a punch or shave biopsy will confirm the diagnosis.
A 55-year-old woman presents for evaluation of a widespread rash that first appeared several months ago. The rash has resisted treatment with various OTC products—antifungal cream (tolnaftate), triple-antibiotic cream, and tea tree oil—and continues to itch terribly at times.
Her primary care provider prescribed oral terbinafine (250 mg/d) for a proposed fungal etiology after viewing the rash with a Wood lamp and performing a KOH prep. A one-month course yielded no relief.
The patient claims to be in good health otherwise. She does admit to going through a stressful period involving job loss, divorce, and care of her aging parents.
EXAMINATION
Multiple papulosquamous papules, nodules, and plaques are located on the patient’s arms, legs, wrists, and sacrum. The lesions range from pinpoint to several centimeters and oval to polygonal. They have a striking purple appearance. On closer inspection, many have a shiny, whitish sheen on the surface.
What is the diagnosis?
This is a classic case of lichen planus (LP), an unusual papulosquamous condition of unknown etiology. In addition to the mentioned areas, it can affect the mucosal surfaces, scalp, genitals, nails, and internal organs.
There is no evidence that the cause is infectious; rather, it appears to be triggered by a reaction to an unknown (possibly autoimmune) antigen. LP targets specific cells and produces a lichenoid reaction, in which the upper level of the dermis is broken down by an apoptotic process. This produces a characteristic sawtooth pattern at the dermoepidermal junction by a pathognomic lymphocytic infiltrate. The surface of the affected skin has a shiny, frosty appearance, also seen in other lichenoid conditions (eg, lichen sclerosus et atrophicus).
Other key diagnostic features are classified as “the Ps”: purple, plaquish, papular, planar (flat-topped), polygonal (multi-angular), penile, pruritic, and puzzling. The last word is key to triggering consideration of the other “Ps.”
LP that affects the scalp and mucosal surfaces can be problematic to treat. Topical steroids are the mainstay, but treatment can also include oral retinoids (acetretin, isotretinoin), methotrexate, antimalarials, and cyclosporine. Furthermore, LP can overlap with other diseases—notably lupus, for which TNF-[a] inhibitors are used with some success. For limited disease, intralesional steroid injections can be used (5 to 10 mg/cc triamcinolone).
This patient achieved good relief with a combination of topical and intralesional steroids. Fortunately, in most cases, the disease eventually resolves on its own.
TAKE-HOME LEARNING POINTS
- Lichen planus is an unusual condition, but the look and distribution seen in this case are fairly typical.
- The classic diagnostic “Ps” include: purple, papular, pruritic, plaquish, planar, and most of all puzzling.
- Wood lamp examination is useless for the most common dermatophytoses, which will not fluoresce; however, KOH preps are useful when correctly interpreted.
- In more obscure cases, a punch or shave biopsy will confirm the diagnosis.