A cholesteatoma is often caused by an inflammation of the middle ear or a malfunction of the Eustachian tube. This usually results in negative pressure in the middle ear. A so-called epitympanal retraction of the eardrum can occur.

Normally, the Eustachian tube conducts air from the back of the nose into the middle ear. This regulates the normal pressure in the middle ear. An allergic reaction, a cold, a cleft lip and palate, radiation or sinusitis can impair the normal function of the Eustachian tube. A vacuum can develop in the middle ear. The vacuum created sucks in parts of the eardrum that have been weakened by inflammation. This can then be the precursor of a cholesteatoma. Very rarely, there are also congenital cholesteatomas. However, the most common cause of cholesteatomas is ear infections.