Cerebellopontine angle (CPA) lipomas account for ~10% of all intracranial lipomas.
Characteristically lipomas of the CPA have the trigeminal nerve, facial nerve and vestibulocochlear nerve coursing through it with the latter two on their way to the internal auditory canal. They are associated with intravestibular lipomas and sensorineural hearing loss.
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Clinical presentation
They are often asymptomatic. Due to their location and the associated cranial nerves, if symptomatic, patients commonly present with trigeminal neuralgia, facial symptoms, hearing deficit, vertigo or tinnitus 4,5.
Radiographic features
CT
They appear as lobulated, non-enhancing, uniform fat density mass (~-100 HU) at the CPA.
MRI
Signal characteristics are those of a lipoma:
T1: high signal
T2: high signal
true FISP/FIESTA: low signal margin due to chemical shift artifact
fat-saturated sequences: shows signal dropout
Differential diagnosis
For a general discussion of the differential, refer to:
the generic article on intracranial lipomas
differentials of a cerebellopontine angle mass
The differential for lesions with high T1 signal includes:
hemorrhagic vestibular schwannoma
thrombosed berry aneurysm