A 32-year-old man from rural India presents with a 4-year history of foul-smelling otorrhea from the left ear. He reports conductive hearing loss and occasional vertigo. Otoscopy reveals a retraction pocket in the posterosuperior quadrant of the tympanum with granulation tissue. 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

## Diagnosis: Acquired Cholesteatoma ### Clinical Presentation **Key Point:** The combination of chronic foul-smelling otorrhea, retraction pocket, ossicular erosion, and lateral semicircular canal erosion on imaging is pathognomonic for acquired cholesteatoma. ### Diagnostic Criteria | Feature | Acquired Cholesteatoma | Congenital Cholesteatoma | |---------|------------------------|-------------------------| | **History** | Chronic ear discharge, often post-USOM | No prior ear disease | | **Otoscopy** | Retraction pocket, granulation tissue | Intact tympanum, white mass behind it | | **Ossicular erosion** | Common (especially stapes/incus) | Rare | | **Age of onset** | Usually childhood/young adult | Detected in childhood | | **Eustachian tube dysfunction** | Yes, primary cause | No | ### Pathophysiology 1. **Retraction pocket formation** → negative middle ear pressure from Eustachian tube dysfunction 2. **Epithelial invagination** → keratinizing squamous epithelium inverts into middle ear 3. **Bone erosion** → osteoclastic activity from chronic inflammation and enzymatic degradation 4. **Complications** → ossicular chain destruction, labyrinthine erosion, facial nerve involvement **High-Yield:** The posterosuperior retraction pocket is the classic location for acquired cholesteatoma due to the weakest point in the tympanic membrane (Shrapnell's membrane). ### Imaging Findings **Clinical Pearl:** HRCT shows: - Ossicular erosion (stapes most common, then incus) - Lateral semicircular canal erosion (as in this case) → vertigo - Scutum erosion - Epitympanic involvement **Key Point:** CT is essential to assess disease extent and rule out complications (facial nerve canal erosion, labyrinthine fistula, tegmental erosion) before surgery. ### Management Algorithm ```mermaid flowchart TD A[Acquired Cholesteatoma diagnosed]:::outcome --> B{Complications present?}:::decision B -->|Yes: Facial nerve, labyrinth, meningitis| C[Urgent surgical intervention]:::urgent B -->|No: Uncomplicated| D[Elective mastoid surgery]:::action D --> E[Canal wall down vs. up approach]:::decision E -->|Extensive disease| F[Canal wall down]:::action E -->|Limited disease| G[Canal wall up with ossiculoplasty]:::action ``` **Mnemonic for complications: FLAMING** - **F**acial nerve paralysis - **L**abyrinthine fistula/vertigo - **A**bscess (extradural/subdural) - **M**eningitis - **I**ntracranial extension - **N**ecrotizing otitis (rare) - **G**ranulation/ossicular erosion