A 12-year-old boy presents with a white pearly mass behind an intact tympanic membrane discovered incidentally during routine examination. There is no otorrhoea and audiometry shows mild conductive hearing loss. What is the embryological basis of this condition?

• A Ingrowth of squamous epithelium through a retraction pocket
• B Metaplasia of middle ear mucosa to squamous epithelium
• C Migration of skin through a marginal perforation
• D Persistence of embryonic epidermoid cell rests (epidermoid formation) ✓

Explanation

Congenital cholesteatoma arises from persistence of epidermoid cell rests normally present in the middle ear during fetal development (epidermoid formation theory by Michaels). These rests normally regress by 33 weeks gestation; failure to regress leads to congenital cholesteatoma behind an intact tympanic membrane with no prior ear disease or surgery. This distinguishes it from acquired cholesteatoma (retraction pocket or marginal perforation origin).

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.