Dumbbell-shaped primitive neuroectodermal tumor mimicking trigeminal schwannoma: a case report and review of literature.

Primitive neuroectodermal tumor (PNET) is presumably of neural crest origin, and cases of supratentorial PNET in adult are extremely rare. We reported a case of PNET presenting as a dumbbell-shaped tumor at the middle cranial fossa of skull base mimicking trigeminal schwannoma both clinically and radiologically. The patient underwent surgery on July 13, 2010, using a combination of subtemporal, pterional and retrosigmoid approaches, to achieve decompression and obtain a histological diagnosis. The patient worsened neurologically two weeks after surgery. Her consciousness level became comatose due to tumor bleeding with compression of the brain stem and her precarious physical condition prevented receiving further treatment with adjuvant radiation therapy and chemotherapy. The correct diagnosis of PNET is important because its management differs dramatically from that for trigeminal schwannoma.