A 28-year-old with CSOM atticoantral type has bony erosion of the lateral wall of the epitympanum seen on HRCT temporal bone. This erosion occurs because the cholesteatoma matrix expands primarily via which mechanism involving osteoclast activation?
- A Direct mechanical pressure causing ischemic necrosis
- B Proteolytic enzyme digestion by Pseudomonas aeruginosa biofilm
- C Autoimmune IgG4-mediated bone destruction
- D Cytokine (IL-1, TNF-α, prostaglandins) mediated osteoclast activation by keratinizing squamous epithelium ✓
Explanation
Cholesteatoma causes bone erosion primarily through enzymatic and cytokine-mediated mechanisms: the keratinizing squamous epithelium matrix secretes pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha), prostaglandins (PGE2), and matrix metalloproteinases that activate osteoclasts causing resorption. Collagenase (MMP-1) and gelatinases directly degrade bone matrix. Direct pressure ischemia plays a secondary role. This molecular understanding explains why cholesteatoma erodes the scutum/lateral attic wall, ossicles (long process of incus is most commonly eroded first), and why surgical excision must achieve clear margins of matrix.
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.