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Case #3
1/25
Demographics: 7 years old, Male
Indication: Screening MRI in patient with tuberous sclerosis

Case #3

Findings

  • Interval enlargement of an enhancing subependymal nodule near the right foramen of Monro measuring 1.5 x 1 cm
  • Multiple additional subcentimeter enhancing subependymal nodules
  • Multiple T2/FLAIR hyperintense cortical and juxtacortical lesions in the bilateral cerebral hemispheres
  • Dilated perivascular spaces in the right greater than left frontal white matter
  • No hydrocephalus
  • Right maxillary sinus mucous retention cyst. Mucosal thickening of bilateral ethmoid air cells

Annotated Images & Illustrations

Enhancing subependymal nodule near the right foramen of Monro (red arrows) which demonstrates growth over a 3-year period, concerning for a subependymal giant cell astrocytoma in this patient with tuberous sclerosis.

Enhancing subependymal nodule near the right foramen of Monro (red arrows) which demonstrates growth over a 3-year period, concerning for a subependymal giant cell astrocytoma in this patient with tuberous sclerosis.

Diagnosis

Subependymal giant cell astrocytoma (SEGA)

Key Imaging Features

  • SEGAs are enhancing subependymal masses, commonly located near the foramen of Monro
  • While SEGAs can be difficult to distinguish from subependymal nodules, growth over time and size exceeding 1 cm favor SEGA

Differential Diagnosis

  • No differential diagnosis in a patient with known tuberous sclerosis

Discussion

  • Subependymal giant cell astrocytomas (SEGAs) are almost exclusively seen in patients with tuberous sclerosis
  • They are thought to arise from subependymal nodules and typically present in later childhood or adolescence
  • The primary concern with SEGAs is the development of hydrocephalus due to ventricular outflow obstruction at the foramen of Monro

Pearls

  • In a patient with tuberous sclerosis, an enlarging subependymal nodule exceeding 1 cm in size near the foramen of Monro is highly concerning for a SEGA
  • Watch closely for associated obstructive hydrocephalus

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