Non-neoplastic keratinizing mass with stratified squamous epithelium, frequently occurring in the meninges, central nervous system, bones of the skull, and most commonly in the middle ear and mastoid region.

Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of their erosive and expansile properties...