A cholesteatoma is an epithelial (skin-based) cyst originating from the tympanic membrane, and is usually associated with eustachian tube dysfunction. Chronic negative pressure in the middle ear space pulls the tympanic membrane inward, creating a pocket or cyst that accumulates epithelial debris. The pocket then grows slowly, and can erode surrounding structures such as the ossicles (middle ear bones), the facial nerve, the inner ear, or even the bone against the brain. The pocket also becomes a source of chronic infection, which usually does not resolve until the cyst is removed. As such, cholesteatomas can cause conductive (mechanical) and/or sensorineural (nerve-damage) hearing loss, facial paralysis, or even meningitis. Cholesteatomas may affect all age groups, and as a fundamentally mechanical problem, usually must be treated surgically with a procedure called a tympanomastoidectomy. A tympanostomy tube may also be inserted to address the underlying eustachian tube dysfunction. A second surgery is often required 6 months after the first to check for regrowth and to correct any ossicular (ear bone) damage. A significant amount of hearing loss can usually be recovered at the second surgery. The recovery from surgery is usually relatively benign, and the risks are usually quite low.
Rarely, children may be born with a so-called congenital cholesteatoma, which is the result of an error of development. These are not usually detected until about 3-6 years of age, and may be mistaken for years as a chronic ear infection. Congenital cholesteatomas generally behave similarly to the more common acquired cholesteatomas described above, with the exception that they are infected less frequently.