Cholesteatoma Mixed Hearing Loss MCQ — NEET PG Practice Question | NEETPGAI
Cholesteatoma Mixed Hearing Loss
medium
ear ENT
A 35-year-old man presents with a 2-year history of painless, foul-smelling otorrhea from the right ear that has not responded to multiple courses of topical antibiotics. Audiometry shows air-bone gap of 25 dB with an additional 15 dB sensorineural component. High-resolution CT temporal bone reveals scutum erosion and long process of incus destruction. The audiometric pattern marked **A** in the diagram represents mixed hearing loss from cholesteatoma with ossicular erosion. Which of the following is the pathophysiological mechanism of bone erosion in this condition?
A. Osteoclast activation via RANK-L signaling pathway and pressure necrosis from keratin accumulation
B. Direct enzymatic degradation of bone matrix by keratinized epithelium
C. Mechanical erosion from chronic negative middle ear pressure alone
D. Inflammatory cytokine production by granulation tissue without osteoclast involvement
Explanation
Why option 1 is correct
Cholesteatoma is a destructive epithelial lesion composed of keratinizing stratified squamous epithelium that accumulates keratin debris in a cystic sac. Bone erosion occurs through two primary mechanisms: (1) osteoclast activation via the RANK-L (receptor activator of nuclear factor-κB ligand) pathway, which is the dominant cellular mechanism of bone resorption, and (2) pressure necrosis from progressive keratin accumulation within the cystic sac. This dual mechanism explains why cholesteatoma causes progressive, relentless bone destruction despite being a non-inflammatory lesion in many cases. The long process of incus is the most commonly eroded ossicle, resulting in the conductive component of the mixed hearing loss pattern shown in A (Cummings Otolaryngology 7e; Scott-Brown's Otorhinolaryngology 8e).
Why each distractor is wrong
Option 2: While cholesteatoma contains keratinized epithelium, the epithelium itself does not directly enzymatically degrade bone. The bone destruction is mediated by recruited osteoclasts, not by epithelial enzymes. This is a common misconception among students who confuse the composition of the lesion with its mechanism of action.
Option 3: Negative middle ear pressure from Eustachian tube dysfunction is the pathogenic pathway that leads to retraction pocket formation and cholesteatoma development, but it is not the mechanism of bone erosion itself. Once the cholesteatoma is established, bone destruction proceeds via osteoclast activation and pressure necrosis, not pressure alone.
Option 4: Although granulation tissue and inflammatory cytokines may be present in some cholesteatomas, the primary and most consistent mechanism of bone erosion is osteoclast-mediated resorption via the RANK-L pathway. Inflammatory cytokines alone cannot account for the progressive, focal bone destruction characteristic of cholesteatoma.
High-YieldNEET PG
Cholesteatoma bone erosion = RANK-L-mediated osteoclast activation + pressure necrosis, not pressure or inflammation alone. This is why surgical excision is the only definitive treatment—no medical therapy can arrest the osteoclastic process.
Cummings Otolaryngology 7e; Scott-Brown's Otorhinolaryngology 8e
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