Primary intramedullary primitive neuroectodermal tumor (PNET)--case report and review of the literature.

Spinal primitive neuroectodermal tumors (PNET) are very rare tumors, and intramedullary localization is even less common. Indeed, amongst the 23 cases of the spinal PNET described in the literature, only eight cases had an intramedullary localization. Following the WHO 2000 classification, PNETs have been considered embryonal tumors composed of undifferentiated neuroepithelial cells with a capacity of differentiation into different cellular lines, such as astrocytic, ependymal, melanotic and muscular. They have been considered to arise from a neoplastic transformation of primitive neuroepithelial cells, thereby making their presence possible in any part of the central nervous system. The optimal treatment for these malignant tumors is not yet clear, although, over the years, radiotherapy has been considered the best treatment for spinal PNETs. The described case is that of a 38-year-old man with a primary intra-extramedullary PNET, treated by laminectomy, open biopsy and chemotherapy. The patient, 18 months after the onset of his symptomatology, died without cerebral tumor involvement.