Concomitant primary angiosarcoma and invasive carcinoma of the breast: a case report.

Collision tumor is a rare entity composed of two different tumors that occur in close to one another and maintain distinct borders. Only few cases have been reported in the breast. We report the first case of concomitant and adjacent primary angiosarcoma (PBAS) and invasive carcinoma of the breast (IBC), in a 45-year-old patient which presented with a lump in her right breast.