Cytokeratin 18 expression in squamous cell carcinoma of the head and neck.

Cytokeratin (CK) expression was studied in squamous cell carcinomas of different subsites in the head and neck by using cryostat sections from 27 head and neck squamous cell carcinomas (HNSCCs) and 6 cell lines established from HNSCC. All tissues were analyzed immunohistochemically with a panel of monospecific anti-keratin monoclonal antibodies. Most carcinomas recapitulated the expression pattern of keratins present in the basal layer of normal epithelium from the site of tumor origin. Regional differences in the expression of simple-epithelial type of keratins in stratified (pseudostratified) epithelia were to a large extent repeated in corresponding carcinomas. In the present study, localization of various keratins were surveyed and CK 18 specific monoclonal antibodies were specifically used to distinguish SCCs of the larynx or hypopharynx from SCCs of the oral cavity. CK 18 staining of almost all tumor cells was detected in 11 of 12 SCCs of the larynx and hypopharynx, but was only detected sporadically in 3 of 9 SCCs of the oral cavity. The present results show that CK 18 typing might be useful for distinguishing sites of origin of various HNSCCs. Findings also indicate that CK 18 expression in SCC might be modulated by microenvironmental factors.