Intracranial peripheral primitive neuroectodermal tumor manifesting as abducens nerve palsy.

INTRODUCTION: Peripheral primitive neuroectodermal tumor (PNET) occurring as an extra-axial lesion within the intracranial space and extending to the subarachnoid space is extremely rare. CASE REPORT: An 18-month-old girl presented with an intracranial peripheral PNET manifesting as abducens nerve palsy. Magnetic resonance imaging on admission revealed a lesion affecting the trigeminal and abducens nerves. The tumor was partially removed via the subtemporal approach. Histological examination showed a high-grade, undifferentiated neoplasm of small cell type with positive immunostaining for MIC2. The histological diagnosis was peripheral PNET. OUTCOME: Craniospinal radiotherapy reduced the tumor size, but adjuvant chemotherapy designed for Ewing's sarcomas and PNETs was not effective. She died 1 month after the last chemotherapy, despite whole craniospinal irradiation (total dose 53.2 Gy) and chemotherapy.