Cholesteatoma, Middle Ear

**Definition:** A mass of KERATIN-producing squamous EPITHELIUM that resembles an inverted (suck-in) bag of skin in the MIDDLE EAR. It arises from the eardrum (TYMPANIC MEMBRANE) and grows into the MIDDLE EAR causing erosion of EAR OSSICLES and MASTOID that contains the INNER EAR.

**Tree numbers:** - C09.218.200 - C17.800.428.260.300

**Synonyms:** - Middle Ear Cholesteatoma - Aural Cholesteatoma