Cytokeratin expression patterns in the human tympanic membrane and external ear canal.

Immunohistochemical investigations were carried out to further reveal the pattern of cytokeratin (CK) expression in middle ear cholesteatoma. Using chain-specific monoclonal antibodies and the indirect immunoperoxidase technique, 10 out of 19 CK polypeptides were screened in cryoslices of fresh postmortem eardrums and external ear canal specimens. Our data, combined with those published before, indicate an intimate relationship between middle ear cholesteatoma lesions and epidermal tissues in the immediate vicinity. Our CK data do not favor the metaplastic origin of cholesteatoma, because the CK complement of cholesteatoma lesions does not include major and typical CK constituents of the middle ear mucosa.