Pityriasis rubra pilaris
Pityriasis rubra pilaris is a condition where the primary lesion is a follicular papule. An erythematous follicularly based papule, often in a small group, appears typically on the upper chest or head and neck. New lesions appear in other areas, and coalesce to form erythematous scaling plaques. Involvement can become generalized, producing an erythroderma.
There are frequently islands of completely normal skin within the otherwise generalized erythroderma. These islands of sparing are a useful diagnostic sign of PRP.
The erythema of PRP may have a "salmon-like" color. Palms and soles can be extensively involved, and nail dystrophy can occur.
PRP may, in children, apparently follow a systemic viral infection. In adults, there is usually no obvious precipitating cause.
- Treatment is difficult.
- The juvenile and adult forms usually clear spontaneously in one to three years.
- Some cases respond to oral methotrexate.
- Oral etretinate, and other systemic retinoids, may be effective in some patients.
- Case reports show benefit from retinoids, methotrexate, azathioprine, calciprotriol, Acitretin, and UVB, Acitretin combined with UVA