Extradural extension of primitive neuroectodermal tumor--case report.

A 13-year-old boy presented with a primitive neuroectodermal tumor (PNET) with unusual extracranial extension. Precontrast computed tomography showed the tumor as a ring-shaped high-density area which was enhanced postcontrast, with a low-density center. Magnetic resonance imaging showed the tumor as a low-intensity area on the T1-weighted images with marked enhancement by gadolinium-diethylenetriaminepentaacetic acid, and high intensity on the T2-weighted images. The central area appeared as high intensity on both images, suggesting free methemoglobin. The tumor was subtotally removed. Histological examination demonstrated PNET. Despite irradiation (20 Gy) to the surgical site, and further tumor removal, he died 6 months later. This case showed PNET can extend extracranially. Diagnosis and treatment of such a tumor located extracranially and intracranially require careful consideration.