Unusual localization of a choroid plexus papilloma in a 4-year-old female.

Choroid plexus papillomas are rare tumors that are confined to areas in which the choroid plexus is normally located. In children, choroid plexus papillomas are predominantly located in the lateral ventricles. Clinically they present with signs of raised intracranial pressure, such as vomiting and increasing head size. Here we report on the clinical, radiologic, and histologic findings of a 4-year-old female who was found to have a tumor in the posterior fossa that had all the histologic hallmarks of a choroid plexus papilloma. This tumor did not originate from the roof of the fourth ventricle as expected but from the ependymal lining covering the median rostral medulla near the pontomedullary junction, a location that so far has not been reported.