A 28-year-old man from rural India presents with a 3-year history of foul-smelling otorrhea from the left ear. He reports conductive hearing loss and occasional vertigo. Otoscopy reveals a marginal perforation with granulation tissue and bone erosion visible at the margins. High-resolution CT temporal bone shows erosion of the ossicular chain and lateral semicircular canal. What is the most likely diagnosis?

## Clinical Diagnosis of Cholesteatoma ### Key Clinical Features in This Case **Key Point:** The combination of marginal perforation, foul-smelling otorrhea, bone erosion, and ossicular chain involvement on imaging is pathognomonic for cholesteatoma. ### Diagnostic Criteria Met | Feature | Significance | |---------|-------------| | Marginal (attic) perforation | Indicates unsafe cholesteatoma | | Foul-smelling discharge | Keratin debris + secondary infection | | Granulation tissue at margins | Chronic inflammatory response | | Ossicular erosion on CT | Bone-eroding property of disease | | Lateral SCC erosion | Risk of labyrinthine fistula | | 3-year chronicity | Indolent progression typical of cholesteatoma | ### Pathophysiology 1. Marginal perforation allows retraction of tympanic membrane 2. Stratified squamous epithelium invaginates into middle ear 3. Keratin accumulation → bone erosion via osteoclast activation 4. Secondary infection → purulent discharge 5. Progressive ossicular and labyrinthine erosion **High-Yield:** Marginal perforation + bone erosion on imaging = cholesteatoma until proven otherwise. This is the single most reliable diagnostic combination. ### Why Imaging Shows Bone Erosion Cholesteatoma is the only chronic otologic disease that reliably erodes bone due to: - Pressure necrosis from expanding keratin mass - Osteoclast-activating cytokines (IL-1, TNF-α) - Proteolytic enzymes from inflammatory cells **Clinical Pearl:** The presence of ossicular erosion (especially stapes superstructure and incus) on CT is virtually diagnostic. Combined with lateral SCC involvement, this indicates an aggressive disease requiring urgent surgical intervention. ### Management Implications This patient requires: 1. **Urgent imaging:** High-resolution CT (already done) ± MRI (diffusion-weighted) for surgical planning 2. **Surgical consultation:** Canal wall-down (CWD) or canal wall-up (CWU) mastoidectomy 3. **Timing:** Elective but not indefinite—risk of labyrinthitis, facial nerve palsy, intracranial complications **Warning:** Do not delay surgery based on symptom severity alone. The imaging findings (SCC erosion) indicate high risk of serious complications.