Introduction. Melanocyte colonization of breast carcinoma by nonneoplastic melanocytes of epidermal origin is a rare and serious condition first described in 1977. We report on the exceptional clinical and pathological features of this migration phenomenon in a 74-year-old patient.Discussion. The pathogenesis by which melanocyte migration takes place is not known, but a breached basement membrane is considered essential.Conclusion. Histological examination and additional staining of skin are essential to differentiate breast cancer melanosis from malignant melanoma.