Subependymal Giant Cell Astrocytoma (SEGA)
Last Updated: March 27, 2020
- Benign tumor of neuroglial origin classically arising in patients with tuberous sclerosis complex (TSC)
- Slow-growing tumor arising in region of germinal matrix, usually near the foramen of Monro where it may obstruct ventricular outflow resulting in noncommunicating hydrocephalus
- WHO grade I
- May arise from subependymal nodules (SEN) near germinal matrix
- Represents a neuroglial migration abnormality
Most common are CNS tumors in TSC patients
- Uncommonly arises in the absence of TSC
- Similar histology to SENs with diagnosis of SEGA based on tumor size and growth
- Autosomal dominant inheritance or de novo mutations of TSC1 and TSC2 genes
- Afflicts children and young adults with TSC (mean age 11 years)
- Presenting symptoms
- Obstructive hydrocephalus
- Headache, nausea, vomiting from increased intracranial pressure
- Rarely, spontaneous tumoral hemorrhage with intraventricular extension
- Worsening seizures/epilepsy
- Good prognosis/curable with total surgical resection
- Treatment: rapamycin and/or surgical resection
- Slowly enlarging, avidly enhancing mass arising near the lateral ventricles/foramen of Monro in patients with tuberous sclerosis complex (TSC)
- Well-defined tumor margins, often lobulated or “frond-like”
- Variable size
- Additional findings of TSC (cortical tubers/dysplasias, SENs)
- Heterogeneously hypo- to isodense to gray matter
- May show calcification, hydrocephalus
- Strong but heterogeneous enhancement on contrast-enhanced CT
- T1WI: hypo- to isointense to gray matter; areas of calcification may appear hyperintense
- T2WI: heterogeneously iso- to hyperintense; calcification appearing hypointense
- FLAIR: heterogeneously hyperintense, periventricular hyperintensity secondary to acute hydrocephalus and transependymal flow of CSF
- T2*/GRE/SWI: black susceptibility artifact from foci of calcification
- T1WI+C: avid enhancement
- DWI: relatively reduced diffusion compared with TSC hamartomas
- MRI with contrast, imaging surveillance of enlarging SENs/SEGA
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD
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