The motility of keratinocytes in cholesteatoma: an ultrastructural approach to epithelial migration.

Eight cases of attico-antral cholesteatoma were studied by transmission electron microscopy concentrating on the mechanisms involved in intercellular adhesion. Desmosomes were found in large numbers throughout the epidermis and were arranged in various orientations around the keratinocytes. Those desmosomes found in the stratum corneum were significantly less dense than those in deeper layers and were associated with a large number of intercellular spaces, which would reduce the cohesive strength of this layer. The tortuous basement membrane features numerous hemidesmosomes along its length. The findings of this study were compared with previous ultrastructural observations made on the pars flaccida and pars tensa of the tympanic membrane and external canal skin. This revealed that the morphological characteristics of cholesteatoma resemble pars flaccida and external canal skin rather than pars tensa. The implications of these findings are discussed.