Figure 1: This subependymal giant-cell astrocytoma (SEGA) is present in its typical location at the foramen of Monro. This lesion is larger than should be seen for other subependymal nodules in tuberous sclerosis. (Left) A FLAIR image demonstrates multiple subcortical hyperintense tubers. A hyperintense right posterior periventricular nodule is also visible. Other calcified subependymal nodules are less evident. (Right) Postcontrast T1WI demonstrates the avid enhancement typical of SEGAs.
- 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 can obstruct ventricular outflow, resulting in noncommunicating hydrocephalus
- WHO grade I
- May arise from subependymal nodules (SENs) near germinal matrix
- Represents a neuroglial migration abnormality
- Most common are CNS tumors in patients with TSC
- 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 TSC
- Well-defined tumor margins, often lobulated or “frond-like”
- Variable size
- Additional findings of TSC (cortical tubers/dysplasias, SENs)
- Heterogeneously hypodense to isodense to gray matter
- May show calcification, hydrocephalus
- Strong but heterogeneous enhancement on contrast-enhanced CT imaging
- T1WI: hypointense to isointense to gray matter; areas of calcification can appear hyperintense
- T2WI: heterogeneously isointense to hyperintense; calcification appearing hypointense
- FLAIR: heterogeneously hyperintense, periventricular hyperintensity secondary to acute hydrocephalus and transependymal flow of cerebrospinal fluid
- T2*/GRE/SWI: black susceptibility artifact from foci of calcification
- T1WI+C: avid enhancement
- DWI: relatively reduced diffusion compared with TSC hamartomas
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