Cholesteatoma is skin that is located in the middle ear or bone behind the ear (mastoid bone). Normally these locations have lining that is similar to the nose (mucosa) instead of skin. Cholesteatoma can form on its own slowly or can result from trauma or previous surgery in the ear. Once skin has entered into these spaces a cyst generally forms that is trapped and slowly enlarges. With time it can damage surrounding structures such as the hearing bones (ossicles), lead to infections and cause hearing loss. In a minority of cases cholesteatoma can cause complete hearing loss on the same side, facial weakness or paralysis, dizziness or infections in and around the brain.
In most cases a cholesteatoma can be diagnosed by looking in the ear. Some cases, such as in ears that had prior surgery, it can be difficult to tell with certainty by looking in the ear. In such cases a CT or even both a CT and MRI may be helpful. In many cases in which the diagnosis can be made by looking into the ear, a CT scan may still be helpful to see the extent of the cholesteatoma and in treatment planning.
Cholesteatoma is primarily a disease treated with surgery. Only in rare instances is it not. The extent and type of surgery is determined by the cholesteatoma itself. In many instances the cholesteatoma needs to be removed from the middle ear. Often it also involves the bone behind the ear, known as the mastoid. The cholesteatoma from the mastoid can be handled in two different ways. The first is to attempt to remove all the cholesteatoma and restore the normal ear anatomy as much as possible. This is call an "intact-canal-wall" or "canal-wall-up" mastoidectomy. This procedure often restores the ear's function and allows for aeration of the middle ear and mastoid after the surgery. In some cases this surgery is staged in order to both verify the cholesteatoma has been removed and to reconstruct the damage done by the cholesteatoma to the hearing bones 6-12 month after the initial surgery. In some cases an intact-canal-wall mastoidectomy cannot be done. Factors that do not allow for this procedure include anatomy and extent of disease. The second method is to open the mastoid into the ear canal. This is call a "canal-wall-down" or "modified-radical" mastoidectomy. In such case the goal is not to remove all the disease, but instead to open it up so that the cholesteatoma is no longer growing or trapped in the mastoid. Your doctor will be able to look in the ear canal and have access to the mastoid to clean and examine in the future. In such cases a small increase in the size of the ear opening is needed, but the external ear otherwise looks unchanged.