Subependymoma

Incidence

Subependymoma is rare.

Macroscopic appearance and general characteristics

Subependymomas present as well-delineated firm nodules in the fourth ventricle or the frontal horn of the lateral ventricle. They occur in adult patients. They are mostly asymptomatic but can cause obstructive hydrocephalus. Subependymomas are classified as grade I.

Microscopic appearance

Subependymoma is a nodular tumor composed of rests of ependymal cells in a dense glial fibrillary matrix. Hemosiderin deposits are commonly seen. Ependymal rosettes are absent. Microcysts and calcification are frequently observed.

Imaging features

- On non-contrast CT the intraventricular mass is well defined, isodense to brain with frequent calcification. Enhancement is minimal or absent.

- On MRI the subependymomas are somewhat hyperintense on T2 WI and hypointense on T1 WI. The tumor can be heterogeneous due to intratumoral cysts or calcification. Contrast enhancement is absent.

Differential diagnosis

Differential diagnosis has to be made from neurocytoma and astrocytoma and is based on the absence of enhancement.

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