[Primary malignant melanoma of the breast]

A 30-year-old woman with malignant melanoma of the breast is reported. She palpated a tumor in the upper outer quadrant of the left breast. Physical examination and mammographic findings suggested a benign tumor and excisional biopsy was performed. A cut surface of the tumor showed a few black spotty lesions. Pathologic examination revealed infiltration of melanoma cells around the mammary glands and ducts and the connective tissue. Melanoma cells were present in the mammary ducts, suggesting that these cells originated from the ductal epithelium.