A 32-year-old woman presents with a 6-month history of foul-smelling otorrhoea from the left ear and progressive conductive hearing loss. Otoscopy reveals a perforation in the posterosuperior quadrant of the tympanic membrane with granulation tissue visible in the external auditory canal. Pure tone audiometry shows air-bone gap of 35 dB. High-resolution CT temporal bone shows erosion of the ossicular chain and scutum. What is the most likely diagnosis?

Explanation

## Clinical Presentation & Diagnosis **Key Point:** Cholesteatoma is a keratinizing squamous epithelium in the middle ear that erodes bone and causes progressive conductive hearing loss with foul-smelling discharge. ### Diagnostic Features in This Case 1. **Posterosuperior perforation** — classic location for cholesteatoma; indicates retraction pocket formation 2. **Foul-smelling otorrhoea** — pathognomonic; due to keratin debris and secondary infection 3. **Granulation tissue in EAC** — suggests chronic inflammation and bone erosion 4. **Ossicular erosion on CT** — hallmark finding; stapes most commonly affected, then malleus and incus 5. **Scutum erosion** — specific to cholesteatoma; indicates aggressive bone resorption 6. **Conductive hearing loss** — from ossicular chain disruption ### Pathophysiology Cholesteatoma arises from: - **Retraction pocket theory** (most common) — negative middle ear pressure → tympanic membrane retracts → keratin accumulates → erosion - **Invagination** of tympanic membrane, usually at Shrapnell's membrane or posterosuperior quadrant ### High-Yield Imaging Findings | Feature | Cholesteatoma | CSOM (non-cholesteatoma) | |---------|---------------|------------------------| | **Scutum erosion** | Present | Absent | | **Ossicular erosion** | Selective (stapes > malleus) | Variable | | **Location** | Posterosuperior | Variable | | **Bone resorption** | Aggressive, well-demarcated | Slow, irregular | | **Granulation** | Keratinous debris | Mucosal inflammation | **Clinical Pearl:** The combination of posterosuperior perforation + foul-smelling discharge + ossicular erosion is virtually diagnostic of cholesteatoma without need for imaging confirmation. **High-Yield:** Cholesteatoma is an **acquired disease** in most cases (retraction pocket mechanism), not congenital. Congenital cholesteatoma occurs with intact tympanic membrane and normal ear canal.