A 40-year-old patient with atticoantral CSOM undergoes high-resolution CT mastoid. The CT shows erosion of the scutum (outer attic wall) with opacification of the epitympanum and middle ear. The pathological process most responsible for bony erosion in this condition is:

• A Direct proteolytic enzymatic erosion by Pseudomonas aeruginosa biofilm
• B Osteoclast activation by cytokines (IL-1, TNF-α, PGE2) from the cholesteatoma matrix ✓
• C Pressure necrosis from mucus accumulation
• D Ischemic necrosis from ossicular vessel thrombosis

Explanation

Cholesteatoma erodes bone primarily through osteoclast-mediated bone resorption driven by cytokines produced by the keratinocyte matrix (IL-1α, IL-1β, TNF-α, prostaglandin E2, and matrix metalloproteinases). These mediators activate osteoclasts at the bone-cholesteatoma interface. The scutum is typically the earliest site of erosion, seen on HRCT as 'blunting of the scutum.' Enzymatic erosion from bacteria and pressure necrosis are less important mechanisms.

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.