Pityriasis rubra pilaris type 1 spontaneously resolving after 20 years.

Pityriasis rubra pilaris (PRP) is an uncommon, idiopathic, papulosquamous eruption. We report a longitudinal study of a patient with PRP type 1 who was treated with retinoid therapy for 9 years and whose symptoms resolved spontaneously after 20 years. There are no data in the literature on the disease course of PRP type 1 persisting beyond the usual 3 years. This case highlights both the extreme chronicity of PRP and the possibility of remission after many years of active disease.