Tumors of the lateral and third ventricles constitute a small portion of supratentorial masses in children. Choroid plexus tumors account for less than 5% of all pediatric intracranial tumors but 10-20% of those occurring in the first year of life. The majority of tumors represent benign papillomas, though malignant lesions can also be seen. Males are more affected than females and the left lateral ventricle is disproportionally affected. Communicating hydrocephalus may occur from overproduction of CSF from the tumor itself, though obstructive hydrocephalus is more common. Less common to arise in a supratentorial location is an ependymoma, much more frequent in the posterior fossa.

A glial tumor at the foramen of Monro is typically associated with tuberous sclerosis and is called a subependymal giant cell astrocytoma. With progressive growth ventricular obstruction occurs. The diagnosis can be inferred if calcified subependymal tubers are present.