Successful Surgery of Exophytic Brainstem Glioma Mimicking Cerebellar-Pontine Angle Tumor: Case Report and Review of Literature.

Background: Nontectal plate exophytic brainstem gliomas with pilocytic histology are rare and occur mainly in children. Because of their eloquent location, therapy usually consists of bioptic histologic verification and radiotherapy in case of progression.

Case Description: We report on a 43-year-old patient who presented with intermittent tinnitus and reduced hearing in his left ear, as well as a slight left-sided ataxia. Magnetic resonance imaging revealed a left-sided solid cystic cerebellar-pontine angle (CPA) tumor completely obliterating the CPA. Radiologically, a solid cystic vestibular schwannoma was diagnosed. Intraoperatively, a glossy-grayish, intensively bleeding tumor without any capsule or delineation to the brainstem or cranial nerves was resected using electrophysiologic monitoring. Postoperative histology revealed a pilocytic astrocytoma. Three months postoperatively, hearing was preserved (pure tone average-35 dB) and ataxia was equal to what it was preoperatively, gradually becoming better. Postoperative magnetic resonance scans demonstrated a complete resection of the tumor with completely restored brainstem contours.

Conclusions: Exophytic brainstem gliomas may occur in the CPA and mimic vestibular schwannoma. Complete resection even with preserved hearing without neurologic deterioration may be feasible.