Pigmented neurofibroma: report of two cases and literature review.

Two cases of pigmented neurofibroma of the skin are reported. In case 1, the tumor was removed from the back of a 55-year-old man with no associated neurofibromatosis. In case 2, the tumor was removed from the abdominal wall of a 21-year-old woman with neurofibromatosis. Both tumors consisted of benign, short spindle cells and multiple foci of scattered melanin-laden cells. In case 1, the spindle cells were arranged in a storiform pattern, resembling features of dermatofibrosarcoma protuberans. Immunohistochemically, the spindle cells of both cases were demonstrated to be positive for S-100 protein and CD34. The melanin-laden cells stained positively for HMB-45. This report describes an additional two cases of pigmented neurofibroma that conform to the new diagnostic criteria for this disease.