Subependymal Giant Cell Astrocytoma
The Common Vein Copyright 2010
Definition
A subependymal giant cell astrocytoma is the most common CNS tumor in the condition tuberous sclerosis, an inherited neurocutaneous phakomatosis transmitted in an autosomal dominant fashion. Tuberous sclerosis is associated with tubers and subependymal glial nodules in most patients while only 6-16% develop subependymal giant cell astrocytomas. SEGAs are thought to arise from preexisting subependymal nodules in the ventricular wall near the foramen of Monro and can result in hydrocephalus.
The cause transformation from a subependymal nodule into a SEGA is uncertain. Histologically theses tumors demonstrate a mixed glioneuronal pattern with a low proliferative index. They rarely demonstrate malignant features.
Clinically patients generally present in the first two decades of life with a SEGA. Presenting symptoms are related to the increased intracranial pressure and seizure, however the seizures are often due to the other CNS lesions including tubers and nodules as seizure activity does not generally change after tumor removal.
Imaging of subependymal giant cell astrocytomas includes CT and MRI. On CT, a SEGA is an isodense to hypodense mass near the foramen of Monro. Calcification or areas of hemorrhage can be focal areas of higher density. On MRI, they are T1 hypointense to white matter and T2 heterogeneous. After contrast administration, these tumors demonstrate enhancement.
Current treatment is surgical resection for symptomatic or enlarging subependymal giant cell astrocytomas. Radiation has not been proven to prevent tumor growth.
From the Archives of the AFIP Cerebral Intraventricular Neoplasms: Radiologic-Pathologic Correlation1Kelly K. Koeller,November 2002 RadioGraphics, 22, 1473-1505.