A 32-year-old man presents with a 6-month history of foul-smelling otorrhea and conductive hearing loss. Otoscopy reveals a retraction pocket in the posterosuperior quadrant of the tympanic membrane with granulation tissue. Which is the investigation of choice to confirm the diagnosis and assess the extent of disease?

## Investigation of Choice for Cholesteatoma **Key Point:** High-resolution computed tomography (HRCT) of the temporal bone is the **investigation of choice** for confirming cholesteatoma and assessing the extent of disease, including bone erosion and surgical planning. ### Why HRCT Temporal Bone is the Answer HRCT temporal bone is the first-line and most widely accepted investigation for cholesteatoma because: 1. **Bone erosion detection:** Exquisitely demonstrates erosion of the scutum, ossicular chain (incus long process most commonly), tegmen tympani, lateral semicircular canal, and facial nerve canal 2. **Extent of disease:** Delineates spread into the mastoid, epitympanum, and posterior fossa 3. **Surgical planning:** Provides the roadmap for tympanomastoid surgery — identifies critical structures at risk 4. **Availability and cost:** Widely available in Indian centers; standard of care per Dhingra's ENT and Hazarika's textbooks 5. **Sensitivity for soft tissue mass:** Demonstrates the soft tissue density mass in Prussak's space or posterosuperior retraction pocket ### Role of HRCT vs MRI-DWI | Feature | HRCT Temporal Bone | MRI-DWI | |---------|-------------------|---------| | Bone erosion detection | **Excellent** | Moderate | | Surgical planning | **Gold standard** | Supplementary | | Initial diagnosis | **First-line** | Second-line | | Residual/recurrent disease | Moderate | **Superior** | | Radiation exposure | Yes (low dose) | No | | Availability in India | **Widespread** | Limited | | Cost | **Lower** | Higher | **Clinical Pearl:** Per standard Indian ENT textbooks (Dhingra, Hazarika) and NEET PG convention, **HRCT temporal bone is the investigation of choice** for initial diagnosis and surgical planning of cholesteatoma. MRI with DWI is increasingly used post-operatively to detect **residual or recurrent disease** (particularly non-echo-planar DWI), but is NOT the primary investigation for initial confirmation. **High-Yield:** The classic triad — foul-smelling otorrhea + conductive hearing loss + posterosuperior retraction pocket with granulation tissue — points to acquired cholesteatoma. HRCT temporal bone confirms the diagnosis, shows the extent of bone destruction, and guides the surgeon. MRI-DWI is reserved for post-surgical surveillance. ### Why Other Options Are Incorrect - **MRI-DWI (B):** Valuable for detecting residual/recurrent cholesteatoma post-operatively; not the first-line investigation for initial diagnosis in standard Indian practice - **Pure tone audiometry (D):** Documents the degree of conductive hearing loss but does not confirm the structural diagnosis - **Otoacoustic emissions (A):** Assesses outer hair cell function; not relevant for cholesteatoma diagnosis *Reference: Dhingra PL, Dhingra S. Diseases of Ear, Nose and Throat & Head and Neck Surgery, 7th ed.; Hazarika P. Textbook of ENT & Head-Neck Surgery.*