This 45-year old woman presented with gray macules on both of her axillae that have been present for 6 months. Erythema dyschromicum perstans (EDP, also known as ashy dermatosis and dermatosis cenicienta) most commonly affects patients of Latin American and Asian descent and is characterized clinically by an extensive and asymptomatic eruption of blue-gray macules. The most common sites affected are the trunk, arms, and face. Females appear to be more commonly affected than males. In the early stages of the disease, the macules are gray and have elevated erythematous borders. With time, these macules assume a blue-gray color, lose their erythematous borders, and coalesce, forming patches that affect large areas of skin. The etiology is unknown although some people believe that EDP is closely related to lichen planus. The diagnosis is usually not problematic because of the characteristic clinical appearance of EDP. Histologically, early lesions may resemble a mild lichenoid dermatitis while the later stages are characterized by only pigment incontinence. The differential diagnosis often includes the late stage of fixed-drug eruption or post-inflammatory pigment alteration (PIPA), but the clinical picture will often distinguish one from the other.
Histologic section of skin shows mild basilar vacuolopathy, a mild lymphocytic perivascular infiltrate, and prominent melanophages in the papillary dermis.