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A cholesterol granuloma (CG) is a benign expansile cystic lesion resulting from a foreign-body reaction to cholesterol crystals, usually within a pneumatized portion of the temporal bone, most commonly the petrous apex.
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Pathogenesis
- Occurs due to obstruction of air cells in the petrous apex or middle ear → hemorrhage into the cavity
- Blood breakdown → release of cholesterol crystals
- These induce a granulomatous foreign-body inflammatory response
- The cyst expands, erodes surrounding bone
Key Factors
- Requires pneumatized petrous apex
- No epithelial lining (unlike true cysts)
- Lined by fibrous tissue with cholesterol clefts, hemosiderin, and multinucleated giant cells
Common Locations
- Petrous apex: Most common site; may affect CN VI (abducens)
- Middle ear/mastoid: Less common
- Frontal and sphenoid sinuses: Rare
Clinical features
| Symptom |
Cause |
| Asymptomatic |
Common; incidental finding |
| Headache / facial pain |
Due to local expansion |
| Hearing loss |
May affect middle or inner ear structures |
| Diplopia |
CN VI palsy via Dorello’s canal (Gradenigo-like presentation) |
| Vertigo or tinnitus |
If inner ear involved |
Radiology