Pigmented breast carcinoma. A clinical and histopathologic simulator of malignant melanoma.

A case of infiltrating breast carcinoma presenting as a pigmented lesion of the areola and nipple is described. The pigmentation was found to be primarily due to interspersed melanocytes and melanophages within the tumor. The histologic criteria and the differential immunohistochemical staining characteristics of melanoma and breast carcinoma are presented. Also emphasized is the difficulty in differentiating pagetoid malignant melanoma and epidermotrophic breast carcinoma.