Lipid-rich versus lipid-secreting carcinoma of the mammary gland.

An unusual case of a malignant breast tumor in a 70 year-old woman is reported. The histological picture displayed a mixed pattern of vacuolated and apocrine-like cells. At electron microscopical level the tumoral cells presented, in a very regular manner, lipidic intracytoplasmic vacuoles. These lipid droplets were secreted by the tumoral cells, and appeared surrounded by SER profiles. A differential diagnosis is discussed with other mammary gland neoplasms, such as histiocytoid carcinoma, apocrine cell carcinoma and other clear cell carcinomas. Based upon our findings we propose that this case should be considered as a lipid secreting carcinoma of the breast.