A congenital cholesteatoma is found in a 3-year-old child as a white pearly mass behind an intact normal tympanic membrane, anterior to the malleus. The most widely accepted theory for the origin of congenital cholesteatoma is:

• A Migration of squamous epithelium through a pre-existing perforation
• B Persistence of an epidermoid formation (ectodermal rest) in the anterosuperior middle ear during embryogenesis ✓
• C Metaplasia of middle ear mucosa to squamous epithelium
• D Invagination of pars tensa in response to Eustachian tube dysfunction

Explanation

Congenital cholesteatoma arises from persistence of the epidermoid formation — an ectodermal cellular rest normally present in the anterosuperior middle ear during fetal development (typically involutes by 33 weeks gestation). Failure of involution leads to progressive accumulation of desquamating keratin, forming a cholesteatoma behind an intact tympanic membrane with no history of ear disease, perforation, or surgery. This is Michaels' theory of epidermoid cell rests. Invagination of pars tensa is the mechanism for acquired cholesteatoma.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.