This 12-year-old boy had a 7 month history of an asymptomatic, erythematous, scaly eruption that began on the trunk and spread to the face, neck, and extremities. He did not improve with topical steroids and was begun on topical tacrolimus ointment. Family history was negative for skin disease. A skin biopsy from his left arm showed acanthosis with overlying alternating foci of ortho- and parakeratosis. Minimal lymphocytic infiltrate was also noted in the upper dermis. Pityriasis Rubra Pilaris (PRP) is a papulosquamous disorder of unknown etiology characterized by abnormal epidermal hyperproliferation. It was first described by Tarral in 1828 and has since classified into 6 categories on the basis of presentation and history: classic adult type, atypical adult type, classic juvenile type, circumscribed juvenile type, atypical juvenile type, and HIV-associated type. Although the majority of cases appear to be acquired, a rare early-onset autosomal dominant inheritance pattern has been reported with onset during early childhood. Two peaks of onset are noted for the acquired form – during the 1st and 5th decades of life.
The eruption usually begins on the head and neck with eventual involvement of the entire body. Follicular hyperkeratotic papules are prominent, progress in a cephalocaudal pattern, and coalesce into orange-red or salmon-colored scaling plaques with well defined borders and “islands of sparing.” Palmoplantar involvement characterized by thickened yellow keratoderma is frequently seen. In addition, scalp, nail and oral mucosal involvement may also be noted.
Approximately 80 percent of patients clear spontaneously within several years, but the course can be quite variable. Childhood PRP is very difficult to treat and has been reported to be poorly responsive to topical steroids and phototherapy. The atypical juvenile variant type occurs during the first few years of life and exhibits a more chronic course. Oral retinoid therapy has proven to be successful in a number of cases. However, given the typically limited disease course, such therapy is generally reserved for persistent cases.
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widespread symmetric salmon-colored plaques with islands of sparing