Acquired dermal melanocytosis: appearance during pregnancy.

We report the first case of acquired dermal melanocytosis (ADM) appearing during pregnancy. A 23-year-old Hispanic woman presented to the Dermatology Clinic of Columbia-Presbyterian Medical Center during the second trimester of pregnancy with a nonpalpable blue-gray patch with interspersed discrete brown macules on the right lower extremity. It had appeared during the first trimester of pregnancy. Cutaneous biopsy specimens revealed dermal melanocytes. A review of all reported cases of this rare dermatosis in the international literature is presented.