A cholesteatoma is a collection of skin cells in a pouch.
The pouch is formed by years of continuous negative pressure in the middle ear (Eustachian Tube Dysfunction) which draws weak sections of the eardrum backwards. New skin cells continuously form in the middle of the ear drum. It slowly moves across the ear drum and then down the ear canal. The skin cells become trapped in a retraction pocket and the ‘pouch’ slowly gets bigger. An enlarged pocket may erode the hearing bones and other structures in the middle ear. The pocket can easily become infected.