Metaplastic breast carcinoma with epithelial phenotype of pseudosarcomatous components

A case of metaplastic breast carcinoma was subjected to an immunohistochemical study to characterize its apparent fibrosarcomatous and chondrosarcomatous elements. Polyclonal and monoclonal antibodies against epithelial cell components such as keratin proteins, epithelial membrane antigen, membrane and cytoplasmic antigens of human mammary carcinoma cells, and carcinoembryonic antigen were used, as well as antibodies against the mesenchymal antigens, desmin, and vimentin. The cells with a mesenchymal appearance had an epithelial derivation, as shown by the presence of epithelial cell markers and absence of mesenchymal cell markers.