Small round cell neoplasm of jaw in a patient with medulloblastoma.

A 24-year-old woman presented with a painful mandibular swelling 6 months after multimodality treatment for a cerebellar medulloblastoma. The tumor was microscopically identical to the cranial neoplasm and a part of widespread dissemination as determined by ancillary studies. Previous concepts of the nonmetastasizing nature of intracranial neuroectodermal neoplasms have been modified by studies on treated cases, surgery being considered a virtual prerequisite for this occurrence. Extracranial neoplastic development of a PNET of CNS origin must be considered in disease-free treated patients up to several years after initial therapy.