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Ganglioglioma

Dr Henry Knipe and Dr Frank Gaillard et al.

Gangliogliomas are uncommon low grade (WHO Grade I or II) CNS tumours which account for around 2% of all primary intracranial tumours; and up to 10% of primary cerebral tumours in children. They are, however, the most frequent of the neuronal-glial CNS neoplasms. Epilepsy is a common clinical presentation and this tumour has a typical occurrence is 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. 

Epidemiology

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.

Clinical presentation

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

Pathology

Gangliogliomas are composed of two cell populations:

  1. ganglion cells (large mature neuronal elements): ganglio-
  2. neoplastic glial elements (primarily astrocytic): -glioma

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 gangliocytomas, which contain essentially only mature neural ganglion cells, and ganglioneurocytoma which in addition have small mature neoplastic neurons.

Markers

Neuronal origin is demonstrated by positivity to neuronal markers:

  • synaptophysin
  • neuronal specific enolase

May also show positivity to the GFAP marker.

Variants
Location

There is predilection towards the temporal lobes 6.

Radiographic features

Imaging findings mirror the various patterns of growth which these tumours may demonstrate, and unfortunately 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 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

Treatment and prognosis

Local resection is the treatment of choice and determines prognosis. In the brain where a reasonable resection margin can be achieved, prognosis is good. In the spinal cord where this is 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.

Differential diagnosis

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

If in the spinal cord consider:


Related articles

Malformations of the central nervous system

 

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