This exhibit depicts the coronal anatomy of the ear with a large cholesteatoma. A cholesteatoma is an expanding growth of skin cells within the middle ear. Cholesteatomas may be congenital (as a result of abnormal epithelial cell development) or acquired as a result of chronic infections. Inflammation of the middle ear leads to poor drainage in the eustachian tube. This creates a vacuum effect, pulling and stretching the tympanic membrane into the middle ear cavity. The stretched eardrum forms a cystic pocket that fills with old skin cells and waste materials. This pocket then expands with infection and forms a cholesteatoma.