Erythema dyschromicum perstans.

Erythema dyschromicum perstans (EDP) was first described in 1957, and electron microscopic studies were reported in 1969. Herein, we describe five cases and compare light and electron microscopic findings, direct and indirect immunofluorescence, and dopa-positive melanocyte counts between normal and affected skin. The results indicate that EDP is a clinically characteristic disorder with a lichenoid reaction in its active phase. This lichenoid reaction leads to a pronounced incontinence of pigment and to decreased numbers of melanocytes and of tyrosinase activity in the involved epidermis. These findings support the suggestion that EDP and lichen planus pigmentosus are possible the same entity. Direct inmunofluorescence and fine structural studies show similar findings to lichen plunus. Patients have low-titer antibodies to extranuclear basal cell components.