Cholesteatoma is a type of skin cyst located in the middle ear
and skull bone (mastoid). Causes, incidence, and risk factors:
Cholesteatoma can be a birth defect (congenital), but it more
commonly occurs as a complication of chronic ear infection .
Poor function in the eustachian tube leads to negative pressure
in the middle ear. This pulls a part of the eardrum (tympanic
membrane) into the middle ear, creating a pocket or cyst that
fills with old skin cells and other waste material. The cyst can
become infected. The cyst may get bigger and break down some of
the middle ear bones or other structures of the ear, affecting
hearing, balance, and possibly function of the facial muscles.
Signs and tests: An ear exam may show a pocket or perforation
(opening) in the eardrum, often with drainage. The deposit of
old skin cells may be visible with a microscope or an otoscope,
a special instrument to view the ear. Sometimes a mass of blood
vessels may be seen in the ear. The following tests may be
performed to rule out