Ependymoma pathophysiology

Morphology
Ependymomas are composed of cells with regular, round to oval nuclei. There is a variably dense fibrillary background. Tumor cells may form gland-like round or elongated structures that resemble the embryologic ependymal canal, with long, delicate processes extending into the lumen; more frequently present are perivascular pseudorosettes in which tumor cells are arranged around vessels with an intervening zone consisting of thin ependymal processes directed toward the wall of the vessel.

Ependymoma tumors
Ependymomas make up about 5% of adult intracranial gliomas and up to 10% of childhood tumors of the central nervous system (CNS). Their occurrence seems to peak at age 5 years and then again at age 34. They develop from cells that line both the hollow cavities of the brain and the canal containing the spinal cord, but they usually arise from the floor of the fourth ventricle, situated in the lower back portion of the brain, where they may produce headache, nausea and vomiting by obstructing the flow of cerebrospinal fluid. This obstruction may also cause hydrocephalus.

About 85% of ependymomas are benign myxopapillary ependymoma (MPE). MPE is a localized and slowly growing, low-grade tumor. Although some ependymomas are of a more anaplastic and malignant type, most of them are not anaplastic. For this reason, well-differentiated ependymomas are usually treated with radiation therapy only. For other ependymomas, total surgical removal is the preferred treatment and those that cannot be totally removed also require radiation therapy. The malignant (anaplastic) varieties of this tumor, malignant ependymoma and the ependymoblastoma, are treated similarly to medulloblastoma but the prognosis is much less favorable. Malignant ependymomas may be treated with a combination of radiation therapy and chemotherapy. Ependymoblastomas, which occur in infants and children younger than 5 years of age, may spread through the cerebrospinal fluid and usually require radiation therapy. The subependymoma, a variant of the ependymoma, is apt to arise in the fourth ventricle but may occur in the septum pellucidum and the cervical spinal cord. It usually affects people over 40 years of age and more often affects men than women. The subependymal giant-cell astrocytoma, also called giant-cell glioma, is typically associated with tuberous sclerosis but can occur independent of that condition. Arising in the walls of the lateral ventricles over the basal ganglia, this tumor tends to cause obstruction when it becomes large. It is a well-encapsulated tumor, however, and generally has a very benign course.

Extraspinal ependymoma (EEP), also known as extradural ependymoma, may be an unusual form of teratoma or may be confused with a sacrococcygeal teratoma.