Metaplastic carcinoma of the breast in a renal transplant recipient. Initial diagnosis by fine needle aspiration cytology and immunocytochemistry.

A 46-year-old woman presented with a mass in the left breast and left axillary lymphadenopathy. Five years earlier she had received a renal transplant from an unrelated donor because of end-stage renal failure secondary to adult polycystic kidney disease. She was on immunosuppression therapy in the form of cyclosporine, azathioprine and prednisolone. Fine needle aspiration cytology of the breast mass showed a metaplastic (sarcomatoid) carcinoma, whereas the axillary lymph node aspirate suggested carcinosarcoma. Immunocytochemical studies revealed dense positivity for vimentin in the sarcomatous component and positivity for epithelial membrane antigen in the epithelial component. Rare cells were positive for cytokeratin. The cytodiagnosis was confirmed by excision biopsy of axillary lymph nodes. The patient died on the fourth postoperative day following left mastectomy and axillary clearance. The histopathology report of the breast tumor showed sarcomatoid carcinoma.