Primitive neuroectodermal tumor

Primitive neuroectodermal tumor, often shortened to PNET, is a malignant neural crest tumor. It is rare and usually occurs in children and young adults under 25, with an overall five-year survival rate of about 53 percent. It takes its name from the fact that most tumor cells derive from neuroectoderm but have not developed and differentiated the way a normal neuron would, so they look primitive under the microscope. PNET belongs to the Ewing family of tumors. It is classified by location into peripheral PNET, now thought to be virtually identical to Ewing sarcoma, and PNET of the central nervous system, which generally means supratentorial tumors, since infratentorial tumors once counted as PNETs are now called medulloblastoma. Management of a central nervous system PNET starts with imaging and biopsy and then combines chemotherapy, radiation and complete surgical resection.