Erythema dyschromicum perstans and lichen planus.

Erythema dyschromicum perstans (EDP) is a cutaneous pigmentary disturbance originally considered to be a variant of erythema perstans. The nosologic identity of EDP has been challenged repeatedly as the number of patients with concurrent EDP-like eruptions and lichenoid disorders has increased. In this report, we describe a woman who had EDP for two years before the onset of classic lichen planus (LP). The active lesions of LP gradually evolved into typical ashy-gray macules of EDP. This case provides further support for the concept that EDP and EDP-like conditions should be classified, in certain instances, as erythema dyschromicum variants of LP.