Ganglioglioma

Gangliogliomas are uncommon usually low-grade CNS tumours. Epilepsy is a common clinical presentation and this tumour has a typical occurrence in the temporal lobes, although they have been described in all parts of the central nervous system.

Their appearance on imaging is very variable: from a partially cystic mass with an enhancing mural nodule (~45% of cases) to a solid mass expanding the overlying gyrus. Contrast enhancement is variable.

Children and young patients are usually affected, and no gender predominance is recognised. It accounts for around 2% (from 0.4-3.8%) of all primary intracranial tumours, and up to 10% of primary cerebral tumours in children.

The most common presentation is with temporal lobe epilepsy, presumably due to the temporal lobes being a favoured location.

Gangliogliomas are WHO grade I tumours most frequently found in the temporal lobes (70%) 6,9 but do occur anywhere in the central nervous system.

In a minority of cases (5%) these tumours show aggressive behaviour and histopathologic features and are then called anaplastic gangliogliomas (WHO grade III) 7,9.  At this stage, no criteria for WHO II gangliogliomas have been established 9

Microscopic appearance

Gangliogliomas, as their name suggests, are composed of two cell populations:

  1. ganglion cells (large mature neuronal elements): ganglio-
  2. neoplastic glial element: -glioma
    • primarily astrocytic, although oligodendroglial or pilocytic astroctytoma components are also enountered 9

The proportion of each component varies widely, and it is the grade of the glial component that determines biological behaviour.

Dedifferentiation into high-grade tumours does occasionally occur, and it is usually the glial component (into a GBM). Only rarely is it the neuronal component (into a neuroblastoma).

They are closely related to both gangliocytomas (which contain only the mature neural ganglion cellular component) and ganglioneurocytoma (which also have small mature neoplastic neurones). 

Immunophenotype

Neuronal origin is demonstrated by positivity to neuronal markers 9:

The glial component may also show cytoplasmic positivity for GFAP

Genetics

BRAF V600E mutations are encountered in 20-60% of cases 9

IDH: negative (if positive then the tumour is most likely a diffuse glioma) 9

Imaging findings mirror the various patterns of growth which these tumours may demonstrate and thus their appearance is very variable. Partially cystic mass with an enhancing mural nodule is seen in ~45% of cases. They may also simply present as a solid mass expanding the overlying gyrus. An infiltrating mass is uncommon and may reflect higher grade.

CT

Findings are of a mass which is often non-specific. General features include:

  • iso- or hypodense
  • frequently calcified ~35%
  • bony remodeling or thinning can indicate the slow growing nature of the tumour
  • enhancement is seen in approximately 50% of cases (involving the solid non-calcified component)
MRI

Reported signal characteristics include:

  • T1
    • solid component iso to hypointense
  • T1 C+ (Gd)
    • solid component variable contrast enhancement
  • T2
    • hyperintense solid component
    • variable signal in the cystic component depending on the amount of proteinaceous material or presence of blood products
    • peritumoral FLAIR/T2 oedema is distinctly uncommon
  • T2* (GE/SWI)
    • calcified areas (common) will show blooming signal loss

Local resection is the treatment of choice and determines prognosis. In the brain, where a reasonable resection margin can be achieved, the prognosis is good, with recurrence-free survival reported to be 97% at 7.5-year follow-up 9.

In contrast, in the spinal cord where complete resection is often not possible without devastating deficits, local recurrence is very common.

If only incomplete resection is achievable, or tumour recurrence occurs then radiotherapy may be of some benefit.

Main differential diagnosis is that of other cortical tumours, with helpful distinguishing features including 1-6:

If in the spinal cord consider:

Malformations of the central nervous system
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Article information

rID: 1368
Section: Pathology
Synonyms or Alternate Spellings:
  • Gangliogliomas

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Cases and figures

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    Case 1: of optic chiasm
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    Case 1: axial T1 C+ image
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    T1 axial post
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    T2 Axial
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    Ganglioglioma
    Case 9
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    Case 10
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    Case 12
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    Case 13: subtle right temporal ganglioglioma
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    Case 14: multiple
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    Case 15
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    Case 16: left temporal region
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