THE LIMITED DIFFERENCE BETWEEN KERATIN PATTERNS OF SQUAMOUS-CELL CARCINOMAS AND ADENOCARCINOMAS IS EXPLICABLE BY BOTH CELL LINEAGE AND STATE OF DIFFERENTIATION OF TUMOR-CELLS

Aim-To study the differentiation of epithelial tissues within their hi stological context, and to identify hypothetically, on the basis of ke ratin pattern, the putative tissue origin of a (metastatic) carcinoma. Methods-Using well characterised monoclonal antibodies against indivi dual keratins 7, 8, 18, and 19, which are predominantly found in colum nar epithelia, and keratins 4, 10, 13, and 14, predominantly expressed in (non)-keratinising squamous epithelia, the keratin patterns for a series of 45 squamous cell carcinomas and 44 adenocarcinomas originati ng from various epithelial tissues were characterised. Results-The pre dominant keratins in all adenocarcinomas proved to be 8, 18, and 19. I n addition, these keratins were also abundantly present in squamous ce ll carcinomas of the lung, cervix, and rectum and, to a lesser extent, of the larynx, oesophagus, and tongue, but not in those of the vulva and skin. Keratins 4, 10, 13, and 14 were present in almost all squamo us cell carcinomas, but also focally in some of the adenocarcinomas st udied. Conclusions-There is a limited differential expression of disti nctive keratin filaments between squamous cell carcinomas and adenocar cinomas. Apparently, squamous cell carcinomas that originate from colu mnar epithelium by squamous metaplasia gain the keratins of squamous c ells but retain the keratins of columnar epithelial cells. However, th e simultaneous expression of two of three squamous keratins (4, 10, an d 13) identifies a squamous cell carcinoma, and thus might be useful i n solving differential diagnostic problems.