An immunocytochemical study of cytokeratin expression in human middle ear cholesteatoma.

An indirect immunofluorescent method with monoclonal anti-cytokeratin antibodies was used to localize various cytokeratins in human middle ear cholesteatoma. The 50 K/58 K and 56.5 K/65-67 K paired cytokeratins are markers of skin type and were found in the specimens of human middle ear cholesteatomas studied. In contrast, the 40 K and 45 K cytokeratins (markers of simple epithelia), the 48 K cytokeratin (marker of hyperproliferative epidermal disease) and the 51 K cytokeratin (marker of internal organ epithelia) were absent in human middle ear cholesteatoma. These findings indicate that the pattern of cytokeratins in human middle ear cholesteatoma is similar to that of skin but is different from those of simple epithelium, internal organ epithelia, and hyperproliferative epidermal disease. These findings also support the skin type epithelial origin of cholesteatoma and strongly favor the migration theory in the genesis of cholesteatomas.