From the case:
Quadrigeminal cistern lipoma
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A fat density mass (confirmed on ROI measurement) is located in the left side of the quadrigeminal plate cistern, consistent with a lipoma.
Case Discussion
Intracranial lipomas, are often incidental and completely asymptomatic. Sometimes they are associated with congenital malformations (not in this case) such as corpus callosal dysgenesis.