A 32-year-old man from rural India presents with a 6-month history of foul-smelling otorrhoea from the left ear and progressive conductive hearing loss. On otoscopy, there is a marginal perforation in the posterosuperior quadrant with granulation tissue and polypoidal mass visible. Pure tone audiometry shows air-bone gap of 35 dB. High-resolution CT temporal bone reveals erosion of the ossicular chain and lateral semicircular canal. What is the most likely diagnosis?

Explanation

## Clinical Presentation & Diagnosis **Key Point:** Cholesteatoma is a chronic ear disease characterized by abnormal keratinizing squamous epithelium in the middle ear and mastoid, with progressive bone erosion. ### Diagnostic Triad 1. **Foul-smelling otorrhoea** — pathognomonic; due to keratin debris and secondary infection 2. **Conductive hearing loss** — from ossicular erosion (malleus, incus, stapes) 3. **Marginal or attic perforation** — typically posterosuperior location ### Otoscopic Findings - Granulation tissue and polypoidal mass (cholesteatoma matrix) - Marginal perforation (not central) - Pus with foul odour and keratin debris ### Imaging (HRCT Temporal Bone) | Feature | Cholesteatoma | Chronic OM | Carcinoma | |---------|---------------|-----------|----------| | Bone erosion | Yes (ossicles, SCC) | Rare | Aggressive | | Marginal perforation | Yes | Central | No perforation | | Keratin density | Hypodense | Fluid | Soft tissue | | Ossicular erosion | Common (incus > stapes) | Rare | Possible | **High-Yield:** Erosion of the **lateral semicircular canal** (as in this case) is a hallmark finding indicating advanced disease with risk of labyrinthitis and vertigo. ### Pathophysiology ```mermaid flowchart TD A[Marginal or attic perforation]:::outcome --> B[Retraction pocket formation]:::outcome B --> C[Squamous epithelium invagination]:::outcome C --> D[Keratin accumulation]:::outcome D --> E[Bone erosion via osteoclast activation]:::action E --> F[Ossicular chain damage]:::outcome E --> G[SCC erosion]:::outcome E --> H[Facial nerve/labyrinth involvement]:::urgent ``` **Clinical Pearl:** The **posterosuperior quadrant** is the most common site for retraction pockets and cholesteatoma formation due to the weakest point of the tympanic membrane (Shrapnell's membrane). **Mnemonic — Complications of Cholesteatoma (ACES):** - **A**ural discharge (foul-smelling) - **C**onductive hearing loss - **E**rosion (ossicles, SCC, facial canal, labyrinth) - **S**uppurative complications (meningitis, brain abscess, lateral sinus thrombosis) ### Management Approach - **Definitive treatment:** Surgical removal (canal wall-up or canal wall-down mastoidectomy) - **Preoperative:** Imaging (HRCT/MRI) to assess extent and complications - **Postoperative:** Hearing aid if residual conductive loss; monitor for recurrence **High-Yield:** Cholesteatoma is a **surgical disease**—medical management (antibiotics, aural toilet) is only temporary; recurrence is common without surgery.