Presentation
Hearing loss on the left.
Patient Data
A large left cerebellar pontine angle mass measuring 3 cm in diameter is demonstrated with extension into the internal acoustic meatus, with central non-enhancing components.
There is marked mass effect on the brainstem with encephalomalacia of the left cerebellar peduncle.
The patient proceeded to translabyrinthine resection.
Histopathology:
MICROSCOPIC DESCRIPTION: The sections show a moderately cellular schwannoma. It mainly contains Antoni A areas with fascicles of spindle cells. Verocay bod formation is seen with palisaded tumor cells. They show no significant nuclear pleomorphism. Focal microcystic change is noted. Mitoses are inconspicuous. There is no evidence of necrosis. The background contains scattered foamy macrophages. No evidence of malignancy is identified.
DIAGNOSIS: Schwannoma.
Case Discussion
Vestibular schwannomas (a.k.a. acoustic neuroma/schwannoma) are the most common cerebellopontine angle mass. Extension into the internal acoustic meatus is a helpful differentiator from meningioma.