Unusual variant of lipid-rich mammary carcinoma.

A variant of lipid-secreting mammary carcinoma shared many of the features of previously reported lipid-rich breast tumors, ultrastructurally as well as clinically and by light microscopy. In addition, electron microscopy confirmed the presence of a dual-cell population where the more aggressive cell, which resembled an altered myoepithelial cell, was responsible for the lipid production. The tumor also demonstrated some similarity to medullary carcinoma and may represent a variant of this type of mammary tumor.