Neurosurgery notes/Tumours/Gliomas, Glioneuronal Tumors, and Neuronal Tumors/Circumscribed astrocytic gliomas/Subependymal giant cell astrocytoma (SEGA)

Subependymal giant cell astrocytoma (SEGA)

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Circumscribed astrocytic gliomas

General

  • Strong associated with tuberous sclerosis syndrome
    • 10% of tuberous sclerosis patients have SEGA
    • One of the major diagnostic criteria of tuberous sclerosis

Definition

  • Essential:
    • Characteristic histological features with multiple glial phenotypes including polygonal cells, gemistocyte-like cells, spindle cells, and ganglionic-like cells ANO
    • Immunoreactivity for glial markers (GFAP, S100) AND
    • Variable expression of neuronal markers (class III p-tubulin. neurofilament, synaptophysin, NeuN)
  • Desirable:
    • Nuclear immunoexpression of thyroid transaction factor I (TTF1)
    • Lost or reduced expression of tuberin and hamartin
    • Immunoexpression of phosphorylated S6
    • DNA methylome profile of subependymal giant cell astrocytoma
    • History of tuberous sclerosis
    • TSC1 or TSC2 mutation

Numbers

  • 25 yrs

CNS WHO grading

  • Grade: 1
    • These are slow-growing, glial neuronal tumors, usually developing over 1-3 years.

Localisation

  • Lateral walls of lateral ventricles adjacent to foramen monro
    • Leaves the overlying ependyma intact
  • Can be unilateral or bilateral

Genetic profile

  • Inactivating mutation in
    • TSC1 gene (9q) → tuberin (prot)
    • TSC2 gene (16p) → hamartin (prot)
      • Interact to form a complex

Clinical presentation

  • Mainly asymptomatic
  • Seizure
  • Obs(x) HCP

Origin

  • Neuroglial progenitor cell
  • Developing from those benign subependymal nodules (hamartomas) located near the foramen of Monro.
    • Development is a gradual process that generally occurs within the first 2 decades of life.

Radiology

  • Solid partly calcified masses
  • T1: iso or hypointense
  • T1+C: Enhances
  • T2: hypertense
  • MR spect: high ratio of choline to creatinine and low ratio of N-acetylaspartate to creatinine
 
2.14 Subependymal giant cell astrocytom extending
Subependymal giant cell astrocytoma extending into the left ventricle and causing hydrocephalus.

Histopathology

Macroscopic

Fig. 2.16 Subependymal giant cell astrocytoma. A Coronal section of the left hemisphere of a patient with tuberous sclerosis, showing a subependymal giant cell astrocytoma (arrowheads) and multiple cortical tubers (arrows). B Multiple subependymal nodules on the walls of the lateral ventricles.
A Coronal section of the left hemisphere of a patient with tuberous sclerosis, showing a subependymal giant cell astrocytoma (arrowheads) and multiple cortical tubers (arrows).
A close-up of a brain AI-generated content may be incorrect.
Fig. 2.16 Subependymal giant cell astrocytoma. A Coronal section of the left hemisphere of a patient with tuberous sclerosis, showing a subependymal giant cell astrocytoma (arrowheads) and multiple cortical tubers (arrows). B Multiple subependymal nodules on the walls of the lateral ventricles.
B Multiple subependymal nodules on the walls of the lateral ventricles.

Microscopic

  • Composed of large plump cells that resembles (similar to gemistocytic astrocytes)
  • Cells arranged in sweeping fascicle, sheets and nests
L A Mixed population Of polygonal to ganglionic-like cells. B Collection of large tumour cells, with perivascular
Subependymal giant cell astrocytoma. A Mixed population of polygonal to ganglionic-like cells. B Collection of large tumour cells, with perivascular pseudorosettes reminiscent of ependymoma.
Fig. 2.17 Subependymal giant cell astrocytoma. A Cellular heterogeneity is typical for these tumours; elongated cells arranged within sweeping fascicles are admixed with large cells. B Infiltration of inflammatory cells, induding mature lymphocytes and mast cells, is a consistent feature. C Multifocal calcification within the tumour and/or blood vessels is commonly seen.
Subependymal giant cell astrocytoma. A Cellular heterogeneity is typical for these tumours; elongated cells arranged within sweeping fascicles are admixed with large cells. B Infiltration of inflammatory cells, including mature lymphocytes and mast cells, is a consistent feature. C Multifocal calcification within the tumour and/or blood vessels is commonly seen.

Management

Conservative

  • Usual practice
  • Serial imaging and clinical follow-up
  • Indicated
    • Asymptomatic

Surgical excision

  • Indicated
    • Asymptomatic SEGA but with continuous growth
    • Symptomatic SEGA
      • Behavioural changes
      • Worsening of seizures
      • Symptoms of Hydrocephalus.
  • Outcome
    • Good for small tumours that can be excised

Stereotactic radiosurgery

  • Indicated for smaller lesions

Chemotherapy

  • mTOR inhibitors
    • Everolimus
    • Indication
      • Children >3 yrs and adults
      • Recurrent SEGA
      • Not surgical resectable
        • Bilateral fornix lesions with high risk of morbidity
      • Not surgical candidates
    • Aim
      • Reduce the recurrence rate of SEGAs
      • Shrinkage of other tumours associated with tuberous sclerosis (angiofibromas and angiomyolipomas)
      • Recurrence of SEGAs after surgery has been found to be low in patients treated with mTOR inhibitors.
      • Stabilize tumour
    • EXIST 1 trial
      • F/U of 28·3 months, 49% patients had a response of > 50% reduction in SEGA volume
      • Side effects: stomatitis and pneumonia
    • Side effects
      • Immunosuppression and recurrent infections,
      • Significant anaemia
      • Thrombocytopenia
      • Fatigue
      • Nausea
      • Diarrhoea

Prognosis

  • Can have leptomeningeal dissemination with drop mets
  • Good outcome with gross total resection.
  • For pt with tuberous sclerosis surveillance by MRI every 3 yrs until 25 yrs old
  • Inhibition of mTOR1 by everolimus might be effective for inoperable tuberous sclerosis associated SEGAs