A 32-year-old man from rural India presents with a 6-month history of foul-smelling otorrhea from the left ear following a suppurative ear infection in childhood. On otoscopy, there is a marginal perforation with granulation tissue and a whitish mass visible in the external auditory canal. Pure tone audiometry shows a conductive hearing loss with an air-bone gap of 35 dB. High-resolution CT temporal bone reveals erosion of the scutum and malleus with soft tissue density in the attic region. What is the most likely diagnosis?

Explanation

## Clinical Presentation and Diagnosis **Key Point:** The combination of foul-smelling otorrhea, marginal perforation, whitish mass in the canal, ossicular erosion (malleus), and scutal erosion on CT is pathognomonic for cholesteatoma. ### Pathophysiology of Cholesteatoma Cholesteatoma is a chronic suppurative otitis media with bone-eroding capability. Two main types exist: | Feature | Attic (Pars Flaccida) | Sinus (Pars Tensa) | |---------|----------------------|--------------------| | **Location** | Attic (epitympanic recess) | Sinus tympani, facial recess | | **Perforation** | Marginal (attic region) | Central | | **Scutal erosion** | Yes, characteristic | No | | **Malleus erosion** | Yes, early | Late or absent | | **Prevalence** | ~80% of cases | ~20% | | **Pathogenesis** | Retraction pocket theory | Retraction + negative pressure | ### Diagnostic Criteria Met in This Case 1. **Marginal perforation** — indicates pars flaccida involvement 2. **Whitish mass** — desquamated keratin and squamous epithelium (the hallmark of cholesteatoma) 3. **Ossicular erosion (malleus)** — bone-eroding property of cholesteatoma 4. **Scutal erosion on CT** — specific to attic cholesteatoma 5. **Conductive hearing loss with air-bone gap** — ossicular involvement 6. **Foul-smelling discharge** — secondary bacterial colonization of the keratinous mass **High-Yield:** Scutal erosion is virtually diagnostic of cholesteatoma and is NOT seen in simple chronic suppurative otitis media. ### Why This Is Attic (Pars Flaccida) Type ```mermaid flowchart TD A[Cholesteatoma]:::outcome --> B{Location of perforation?}:::decision B -->|Marginal/attic| C[Pars Flaccida Type]:::outcome B -->|Central| D[Pars Tensa Type]:::outcome C --> E[Scutal erosion + malleus erosion]:::action D --> F[Sinus tympani involvement]:::action E --> G[Attic cholesteatoma confirmed]:::outcome F --> H[Sinus cholesteatoma]:::outcome ``` **Clinical Pearl:** The pars flaccida (Shrapnell's membrane) is the weakest part of the tympanic membrane and most prone to retraction, making attic cholesteatoma the most common type in children and young adults. **Mnemonic for cholesteatoma complications — SODA:** - **S** — Sensorineural hearing loss (labyrinthine erosion) - **O** — Ossicular erosion (malleus, incus, stapes) - **D** — Dural erosion (meningitis, brain abscess) - **A** — Acute mastoiditis, facial nerve paralysis [cite:Dhingra 8e Ch 8]