Abstract
BACKGROUND: True carcinosarcoma of the breast is an extremely rare condition, accounting for 0.08-0.2% of all breast malignancies. The correct definition of this tumor requires both a carcinomatous component and a malignant non-epithelial component of mesenchymal origin, without evidence of a transition zone between the two elements. CASE PRESENTATION: We present a case of a 49-year-old woman presenting with a 4cm mass at the level of her left breast upper-outer quadrant with a histologic diagnosis of true carcinosarcoma of the breast. DISCUSSION: The most appropriate therapeutic regimens for breast carcinosarcoma are still unclear because of the rarity of this condition, but Breast Conserving Treatment (BCT) followed by adjuvant chemotherapy seems to provide a prognosis equalling that of usual Invasive Ductal Carcinoma of the breast.