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Subependymal Giant Cell Astrocytoma

Last Updated: March 20, 2021

Open Table of Contents: Subependymal Giant Cell Astrocytoma

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.

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.

BASIC DESCRIPTION

  • 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

PATHOLOGY

  • 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

CLINICAL FEATURES

  • 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

IMAGING FINDINGS

  • General
    • 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)
  • CT
    • Heterogeneously hypodense to isodense to gray matter
    • May show calcification, hydrocephalus
    • Strong but heterogeneous enhancement on contrast-enhanced CT imaging
  • MRI
    • 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

IMAGING RECOMMENDATIONS

  • MRI with contrast, imaging surveillance of enlarging SENs/SEGA

For more information, please see the corresponding chapter in Radiopaedia.

Contributor: Rachel Seltman, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.01.38

References

Kalantari BN, Salamon N. Neuroimaging of tuberous sclerosis: spectrum of pathologic findings and frontiers in imaging. AJR Am J Roentgenol 2008;190: W304–W309.

Louis DN, Ohgaki H, Wiestler OD, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114:547.

Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Philadelphia, PA: Elsevier; 2016.

Roth J, Roach ES, Bartels U, et al. Subependymal giant cell astrocytoma: diagnosis, screening, and treatment. Recommendations from the International Tuberous Sclerosis Complex Consensus Conference 2012. Pediatr Neurol 2013;49:439–444.

Sener RN. Diffusion MR imaging of giant cell tumors in tuberous sclerosis. J Comput Assist Tomogr 2003;27:431–433.

Smith A, Smirniotopoulos J, Horkanyne-Szakaly I. From the radiologic pathology archives: intraventricular neoplasms: radiologic-pathologic correlation. Radiographics 2013;33: 21–43.

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