Lichen planus.

Lichen planus, a papulosquamous disease, in its classical presentation is characterized by pruritic violaceous papules most commonly on the extremities of middle-aged adults. It may or may not be accompanied by oral and genital mucous membrane involvement. Its course is generally self-limited for a period of several months to years, but it may last indefinitely. There are many clinical variants described, ranging from lichenoid drug eruptions to association with other diseases such as diabetes mellitus, autoimmune disease, and the graft-versus-host reaction. The relationship of these, if any, to classical lichen planus is questionable. Multiple therapeutic options exist including corticosteroids, retinoids, griseofulvin, PUVA, and cyclosporine.