Pityriasis rubra pilaris: a review of diagnosis and treatment.

The diagnosis of pityriasis rubra pilaris is based essentially on characteristic clinical features. Although the histologic features are not pathognomonic, a lesional skin biopsy for evaluation is important to rule out other papulosquamous and erythematous disorders. The presence of prominent seborrheic keratoses occurring in two cases of pityriasis rubra pilaris is presented. Our understanding of the relationship between vitamin A metabolism and pityriasis rubra pilaris is discussed. Currently available systemic therapeutic modalities for pityriasis rubra pilaris are reviewed. Although pityriasis rubra pilaris does not represent a vitamin A deficiency state, it is responsive to isotretinoin, etretinate, and vitamin A. Antimetabolites remain an alternative therapy.