Features are suggestive of an extra-axial fatty lesion, characteristic of a quadrigeminal cistern lipoma. The fat drops along the vermis could make a disrupted dermoid cyst a possibility, but lipoma can have local extension.

Quadrigeminal cistern lipoma is the second commonest site for intracranial lipomas after pericallosal lipoma. Intracranial lipomas can produce susceptibility artefact that makes it appear dark or blooming on a SWI sequence and so shouldn't be confused with cisternal hemorrhage.