A 28-year-old man from rural Maharashtra presents with a 6-month history of foul-smelling purulent otorrhea from the left ear and progressive conductive hearing loss. Otoscopy reveals a central perforation with granulation tissue and polyps in the external auditory canal. Pure tone audiometry shows bone conduction thresholds within normal limits. High-resolution CT temporal bone shows erosion of the ossicular chain with intact stapes footplate. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis **Key Point:** The combination of central perforation, granulation tissue, polyps, ossicular erosion, and intact stapes footplate is pathognomonic for chronic suppurative otitis media (CSOM) with ossicular chain damage. ## Distinguishing Features | Feature | CSOM | Cholesteatoma | Otitis Externa | Otosclerosis | |---------|------|---------------|----------------|---------------| | **Perforation type** | Central | Marginal/attic | None | None | | **Granulation/polyps** | Yes | Rare | No | No | | **Ossicular erosion** | Common (incus > malleus) | Yes (all three) | No | No | | **Stapes footplate** | Intact | Often eroded | N/A | Stapes fixation | | **CT findings** | Mucosal thickening | Bone erosion, scutum | Soft tissue swelling | Cochlear capsule | | **Bone conduction** | Normal | Normal | Normal | Elevated thresholds | **High-Yield:** In CSOM, the **incus is eroded first** (most common), followed by the malleus. The stapes is typically spared because it is protected by the stapes footplate and oval window niche. This pattern differentiates CSOM from cholesteatoma, which erodes all three ossicles indiscriminately. ## Pathophysiology 1. Chronic mucosal inflammation and osteitis 2. Granulation tissue formation 3. Enzymatic and mechanical bone resorption 4. Ossicular chain erosion (incus > malleus > stapes) 5. Conductive hearing loss (bone conduction preserved) **Clinical Pearl:** The presence of a **central perforation** (not marginal) and **intact stapes footplate** on imaging strongly favors CSOM over cholesteatoma. Cholesteatoma typically causes marginal or attic perforations and erodes all three ossicles, including the stapes footplate. **Mnemonic:** CSOM Ossicular Erosion Pattern — **"I-M-S"** (Incus > Malleus > Stapes, in order of frequency). Stapes is last because it is protected by the oval window niche. ## Management Implications - **Audiological:** Ossiculoplasty (PORP/TORP) after disease control - **Surgical:** Canal wall-up tympanoplasty with ossicular reconstruction - **Medical:** Topical antibiotics, aural toilet, control of infection before surgery