Cytokeratins 7 and 14 in special types of invasive breast carcinomas.

Cytokeratins are typical constituents of the cytoskeleton of the epithelial cells and some other cell types. In normal breast tissue the luminal epithelium of the ducts and acini consistently expresses cytokeratin 7 (as well as 8, 18 and 19) while the myoepithelial cells are consistently cytokeratin 14-positive. We studied 20 invasive lobular, 10 medullary and 10 tubular breast carcinomas on expression of cytokeratins 7 and 14 using monoclonal primary antibodies in an automatic immunochemical system. All the carcinomas were cytokeratin 7-positive, but the percentage of positively stained tumor cells varied. The tumor cells of two medullary carcinomas expressed cytokeratin 14, a finding which can be interpreted as a result of squamous differentiation. Mapping of the cytokeratin profile of the special type of breast carcinomas has a practical importance for a more successful typing of adenocarcinomas in primary and metastatic sites.