Carcinosarcoma of the breast. Immunohistochemical and ultrastructural studies.

A case of a carcinosarcoma in the breast of a 51-year-old woman is described. The tumor consisted of two diversely differentiated components with cells possessing epithelial and mesenchymal characteristics. Plenty of cytokeratin and CEA were immunohistochemically recordable from the carcinomatous component. Some neoplastic cells also stained positively for actin, S-100 protein and smooth muscle antigen. The sarcomatous component was positive only for vimentin. Electron microscopic analysis revealed presence of the following cell types: epithelial cells, myoepithelial cells and polymorphous mesenchymal cells.