Primitive Neuroectodermal Tumor Presenting As a Delayed Sequela to Cranial Irradiation and Intrathecal Methotrexate

A patient developed a primitive neuroectodermal tumor (PNET) many years after therapeutic cerebral radiation and methotrexate treatment for leukemia. The differential radiologic and histologic diagnoses, as well as the possible co-oncogenic effects of radiation and methotrexate, are evaluated.