The ear drum has a skin type lining and like skin elsewhere sheds. In the ear there is a complex mechanism that operates as a conveyer belt to remove the shed skin from the ear drum and ear canal transporting it out of the ear and preventing debris build up.
If the ear drum, or part of it, is sucked in and forms a pocket this mechanism can stop working and the skin becomes trapped and stagnant. The stagnant debris can then become infected and for reasons that are still not well understood the pocket can slowly expand- this is termed cholesteatoma. This pocket can erode through bone as it expands including some of the most dense bone in the human body. Nothing stops this expansion and the only way to deal with the condition is to surgically remove it-mastoid surgery. Cholesteatoma most commonly arises from a pocket (retraction pocket) of the ear drum but can also develop after previous ear surgery, from the edge of a perforation and in some cases a person may be born with cholesteatoma behind an normal ear drum (congenital cholesteatoma).
Cholesteatoma may be diagnosed incidentally or may be identified because of the symptoms it can cause - typically pain-free discharge from the ear and/or hearing loss. The condition can give rise to serious complications. Although none of these complications are common the risk remains whilst the cholesteatoma remains. Specifically the condition can give rise to damage in the ear causing hearing loss, tinnitus, dizziness, perforation of the ear drum and weakness of the muscles of the face. It can also cause damage outwith the ear to surrounding structures and in particular meningitis, abscesses in the brain and clotting (thrombosis) of a large vein inside the skull. It is to avoid these complications and to deal with the discharge that surgery is typically recommended. It is important to note that the size of the cholesteatoma does not reliably predict the risk of complications. Surgery is generally prioritised on a routine non-urgent basis as the risk of developing complications over months is low although CT scan findings or symptoms may dictate otherwise.
white debris at top of ear drum (attic)