The role of retraction pockets in cholesteatoma development: an ultrastructural study.

Persistent retraction pockets causes erosion by adhering to ossicles and other structures of the middle ear. These are characterized by lysis of fibrous layer. Being in contact the squamous epithelium and the middle ear mucosa, it comprises the precursor mechanism of cholesteatoma. The present study discards the classical theories assuming epithelial migration through marginal or attic perforation; and demonstrates that these secondarily develop as a result of cholesteatoma. Retraction pocket specimens obtained from 10 cases of adhesive otitis media were examined with light and transmission electron microscopy and the presence of papillary ingrowth of the squamous epithelium was demonstrated.