Subependymoma
# Subependymoma

A subependymoma is a type of brain tumor; specifically, it is a rare form of ependymal tumor. They are usually in middle aged people. Earlier, they were called subependymal astrocytomas.

The prognosis for a subependymoma is better than for most ependymal tumors, and it is considered a grade I tumor in the World Health Organization (WHO) classification.

They are classically found within the fourth ventricle, typically have a well demarcated interface to normal tissue and do not usually extend into the brain parenchyma, like ependymomas often do.

## Symptoms and signs

Patients are often asymptomatic, and are incidentally diagnosed. Larger tumours are often with increased intracranial pressure.

## Pathology

These tumours are small, no more than two centimeters across, coming from the ependyma. The best way to distinguish it from a subependymal giant cell astrocytoma is the size.

## Diagnosis

The diagnosis is based on tissue, e.g. a biopsy. Histologically subependymomas consistent of microcystic spaces and bland appearing cells without appreciable nuclear atypia or mitoses. The nuclei tend to form clusters.

On a CT, it often shows a less dense to equally dense mass. If it is big, it may have parts that are cystic or calcific. In 50-60% of cases, the tumor is in the fourth ventricle, while the second most common (30-40% of cases) location is the side ventricles. It is rare for it to be in the third ventricle or the central canal of the spinal cord.

## Treatment

Asymptomatic cases may only need watchful waiting. If symptomatic, it can be surgically removed, and partial removal also carries an excellent prognosis.

## Prognosis

The outlook of a cure is extremely favorable.

