Fine needle aspiration cytology of lipid-secreting carcinoma of the breast. A case report.

Fine needle aspiration (FNA) cytology of lipid-secreting carcinoma of the breast was performed on a 43-year-old woman who was admitted with a left breast tumor. Smears of the aspirate showed atypical cells that contained numerous large and small vacuoles in the cytoplasm and were diagnosed as adenocarcinoma of the breast. A modified radical mastectomy was performed under the diagnosis of breast carcinoma. A solid, yellowish, milky white, well-demarcated tumor was found in the resected specimen. Microscopically, hematoxylin and eosin staining revealed foamy and granular vacuoles in the cytoplasm of the tumor cells similar to those seen on the smears, which were positive for lipid staining. Electron microscopic examination also showed numerous intracytoplasmic lipid droplets in the tumor cells. This tumor was finally diagnosed as lipid-secreting carcinoma of the breast on the basis of histologic and electron microscopic features. Lipid-secreting carcinoma of the breast is rare, and only one recurrent case diagnosed by cytology in pleural and pericardial fluids has been described. Since the tumor cells originating in lipid-secreting carcinoma of the breast differ from ordinary breast carcinoma cells, FNA cytology is useful in diagnosing this neoplasm.