Melanocyte chemotactic factor produced by skin metastases of a breast carcinoma

A 65-year-old woman underwent right modified radical mastectomy for a malignant lesion which had developed just below the right nipple. Two years after the operation, skin lesions composed of dark brown to black, pigmented, papular lesions developed in the precordia. A biopsy revealed this to be a cutaneous metastasis of the previous breast carcinoma. However numerous pigment blockade melanocytes were also found in the tumor nests, located in and/or beneath the epidermis. Although a black-colored breast carcinoma has been reported, the presence of pigment blockade melanocytes was not determined. Culture of the tumor nest recovered a population of melanocytes as well as the carcinoma cells. Boyden chamber analysis revealed the presence of a chemotactic factor for melanocytes in the culture medium. This seems to be the first documentation of melanocyte incorporation in breast carcinoma tissue.