A cholesteatoma is a skin growth that occurs in an abnormal location, the middle ear behind the eardrum. It is usually due to repeated infection, which causes an ingrowth of the skin of the eardrum. Cholesteatomas often take the form of a cyst or pouch that sheds layers of old skin that builds up inside the ear. Over time, the cholesteatoma can increase in size and destroy the surrounding delicate bones of the middle ear. Hearing loss, dizziness, and facial muscle paralysis are rare but can result from continued cholesteatoma growth.