- 1. A mass of keratinized squamous cell epithelium and cholesterol in the middle ear, usually resulting from chronic otitis media, with squamous metaplasia or extension of squamous epithelium inward to line an expanding cystic cavity that may involve the mastoid and erode surrounding bone. 2. An epidermoid cyst arising in the central nervous system in humans or animals. [cholesterol + G. stear (steat-), tallow, + -oma, tumor]
* * *1) an epidermoid cyst usu. in the brain arising from aberrant embryonic rests and appearing as a compact shiny flaky mass called also pearly tumor2) a tumor usu. growing in a confined space (as the middle ear or mastoid) and frequently constituting a sequel to chronic otitis mediacho·les·te·a·to·ma·tous -mət-əs adj
* * *n.a skin-lined sac containing debris from dead skin cells that grows from the eardrum into the mastoid bone, eroding normal structures in its path. Left untreated, it can carry infection to the brain, causing meningitis or a cerebral abscess. Treatment is by means of mastoidectomy. Rarely, cholesteatoma can arise congenitally in the temporal bone or central nervous system.
* * *cho·le·ste·a·to·ma (ko″lə-ste″ə-toґmə) [chole- + steatoma] a cystlike mass or benign tumor lined with stratified squamous epithelium, usually keratinizing, and filled with desquamating debris often including cholesterol. Cholesteatomas are most common in the middle ear and mastoid region secondary to trauma or infection that heals improperly so that epithelium invaginates. A congenital variety (see congenital c.), resulting from embryonic inclusions, is less common.
Medical dictionary. 2011.