Quadrigeminal Cistern Lipoma

This patient was scanned for possible temporal lobe epilepsy - an incidental fatty mass of the quadrigeminal cistern was identified.
Quadrigeminal cistern lipomas make up approximately 10 - 25% of all intracranial lipomas, and may be associated with hypoplasia of the inferior colliculi or agenesis of the corpus callosum.
The differential includes:
thrombosed berry aneurysm - often will have calcified rim, and haemosiderin staining.
white epidermoid - rare, and will restrict on DWI
intracranial dermoid - if ruptured will often have multiple droplets.
intracranial teratoma
lipomatous transformation of neoplasm - PNETs, ependymomas, gliomas
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References:
1. L.A. Loevner Brain Imaging - Case review
2. StatDx.com
Credit: Dr Frank Gaillard
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