Ganglioglioma

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Ganglioglioma
GgMRI.jpg
Axial MRI of right temporal ganglioglioma
Tumor Class Astrocytoma
Cell of origin Glial precursor
Survival Dependent on WHO grade
Histologic Features
Radiographic Features

Contents

Definition

Ganglioglioma is a well-differentiated, slowly growing biphasic neuroepithelial tumor composed of neoplastic mature ganglion cells and neoplastic glial cells. Ganglioglioma is considered a WHO Grade I or II tumor, though some lesions may be considered WHO Grade III or IV based on the degree of malignancy of the glial component.

Epidemiology

Gangliogliomas represents less than 1% of all brain tumors. The peak incidence is in children and young adults between age 8.5 and 25 years, with a mean age of occurrence at 9.5 years. There is a slight female predominance (1.1:1).

Localization

Gangliogliomas may occur throughout the CNS, but are most commonly found in the temporal lobes.

Clinical presentation

Symptoms are site-specific, but are stereotypically long-standing. Ganglioglioma is the most common tumor associated with chronic temporal lobe epilepsy. Seizures are the most common presenting symptom.

Imaging

MRI demonstrates a well-demarcated lesion with variable contrast enhancement. Scalloping of the calvarium may be seen adjacent to superficially located tumors. On non contrast CT, the lesions are hypodense with scattered hyperdensities from calcification.


Macroscopy

Gangliogliomas are solid or cystic tumors that are well delineated from the surrounding normal brain. Calcifications may be present.

Histopathology

Gangliogliomas are well-differentiated, slowly growing biphasic neuroepithelial tumors composed of neoplastic mature ganglion cells and neoplastic glial cells. Occassional mitoses may be present. Grading is based upon the degree of malignancy seen in the glial component of the tumor. Microscopically, the ganglion cells demonstrate nerve cell differentiation. They are synaptophysin positive.
Microscopy of ganglioglioma.  Note the binucleated neuron

Molecular genetics

A splice-site-specific polymorphism in the TSC2 gene on chromosome 16p13.3 may predispose to development of sporadic ganglioglioma.

Prognosis

Mean survival time depends on the malignant grade of the glial component of the tumor. WHO Grade I tumors are surgically curable. Higher-grade lesions behave similarly to their glial analogs.

  • i. Ganglion cell neoplasms present in the first three decades with the first symptoms usually epilepsy; predilection for the temporal lobe causing complex partial seizures; often form a cyst with a mural nodule
  • ii. Contain both disorganized ganglion cells with round nucleus, prominent nucleolus, and Nissl substance along with neoplastic glial cells which greatly outnumber the ganglion cells
  • iii. Stain with both synaptophysin and GFAP with low Ki-67 labeling
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