Eruptive dermatosis papulosa nigra as a possible sign of internal malignancy

A 42-year-old black woman presented with dermatosis papulosa nigra lesions of 15 years' duration. Coincident with the diagnosis of symptomatic iron-deficiency anemia about 1 year ago, she reported an "explosion" in number and size of the lesions progressing from her face to her trunk and arms. Physical examination revealed numerous 1-5-mm, black, smooth, verrucous papules predominantly on the forehead, malar region of the face, neck, and upper trunk (Figs 1 and 2). The lesions on the back were situated in a "Christmas tree" pattern and included two 1-cm papules. She had multiple 1-mm papules on the upper arms. A biopsy confirmed the diagnosis of dermatosis papulosa nigra, showing parakeratosis, acanthosis, hyperpigmentation, thick interwoven tracts of epithelial cells, and horn cysts. Given the eruptive nature of her disease, the possibility of an underlying malignancy was entertained. Six weeks later, she went to the emergency room for severe weakness; a colonoscopy revealed an ascending colon adenocarcinoma with a negative metastatic work-up.