A CT of temporal bone in a patient with CSOM shows a 'crescent sign' — a peripheral rim of hypodensity around a soft tissue mass filling the epitympanum. This finding is most consistent with:
- A Glomus tympanicum (paraganglioma) with peripheral hemorrhage
- B Chronic granulation tissue with central vascular necrosis
- C Cholesteatoma with a characteristic matrix of stratified squamous epithelium visible as a hypodense rim ✓
- D Cholesterol granuloma with peripheral lipid deposits
Correct answer: C. Cholesteatoma with a characteristic matrix of stratified squamous epithelium visible as a hypodense rim
Explanation
The crescent sign (or 'blunting of the scutum' with peripheral hypodensity) on CT is characteristic of cholesteatoma. On DWI-MRI, cholesteatoma shows restricted diffusion (bright on DWI, dark on ADC map) due to the keratin debris — this is the gold standard non-invasive method to distinguish cholesteatoma from granulation tissue and is used for residual/recurrent cholesteatoma surveillance. The CT finding of scutum erosion and soft tissue filling the epitympanum with peripheral hypodensity corresponds to the keratinous matrix.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.