Congenital CNS primitive neuroectodermal tumor: case report and review of the literature.

A 30-week gestational age male fetus was found to have a congenital neoplasm involving the posterior cranial fossa, identified by fetal ultrasound examination in utero. Histological and immunohistochemical examination confirmed a diagnosis of primitive neuroectodermal tumor (PNET) of the posterior fossa, also referred to as medulloblastoma. Although PNETs have been well documented, there are relatively few reports of these occurring as congenital neoplasms. We present a case of an in utero, congenital PNET with a review of the literature and discussion of the criteria defining congenital tumors.