A 38-year-old patient with chronic ear discharge undergoes surgery. Intraoperatively, the surgeon finds a pearly white mass eroding the posterosuperior canal wall, involving the attic and destroying the long process of the incus. The mass stains positive for CK5/6 and p63 on immunohistochemistry. The underlying pathogenesis most consistent with this is:
- A Metaplasia of the middle ear mucosa to squamous epithelium (metaplasia theory)
- B Haematogenous spread of a squamous cell carcinoma from a primary site
- C Immigration of keratinizing squamous epithelium through an attic retraction pocket (invasion theory) ✓
- D Ossicular chain hyperostosis with secondary infection
Correct answer: C. Immigration of keratinizing squamous epithelium through an attic retraction pocket (invasion theory)
Explanation
Acquired cholesteatoma most commonly forms through the retraction pocket theory: negative middle ear pressure causes attic retraction of the pars flaccida, and keratinizing squamous epithelium migrates inward, accumulating in the middle ear. The epithelium produces enzymes (collagenase, interleukins) that erode bone. CK5/6 and p63 positivity confirms squamous epithelial origin, not carcinoma. The metaplasia theory (conversion of cuboidal middle ear mucosa to stratified squamous epithelium) is less accepted.
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.