Left temporal ganglioglioma

Case contributed by Dr Rajalakshmi Ramesh

Presentation

Complex partial seizures

Patient Data

Age: 39
Gender: Female
MRI

There is a focal, cortically based lesion in the posterior aspect of the left inferior temporal gyrus. In this region, there is abnormal increased FLAIR signal with apparent mild cortical thickening/disorganisation. There are some areas of low T1 signal on this region. The left hippocampus has minimally increased FLAIR signal but normal size and internal architecture. No pathological contrast enhancement detected. Spectroscopy through the lesion shows reduced NAA and increased myoinositol within the lesion, as well as a small lactate peak. The findings in the posterior aspect of the left inferior temporal gyrus may represent an area of cortical dysplasia or a cortically based tumour such as DNET, oligodendroglioma or ganglioglioma.

The patient’s seizures were managed with levetiracetam, primidone, keppra and lacosamide and she subsequently underwent a sterotactic left temporal craniotomy and resection of the lesion.

Histopathology

MACROSCOPIC DESCRIPTION:

Oval shaped rubbery fawn tissue consistent with low grade astrocytoma/ganglioglioma.

MICROSCOPIC DESCRIPTION:

The sections show a moderately cellular glioneuronal tumour involving both the cortex and white matter.  There is tumour in the subpial region.  Increased numbers of abnormal ganglion cells are present.  They are unevenly distributed with crowding.  They have enlarged nuclei and prominent nucleoli. Bi-nucleated forms are occasionally seen.  A second neoplastic astrocytic proliferation is identified.  The astrocytes form diffuse sheets in a fibrillary background.  They have elongated hyperchromatic nuclei and scanty ill-defined cytoplasm.  Eosinophilic granular bodies are not seen. Mitoses are inconspicuous.  There is no endothelial cell hyperplasia or necrosis. A small amount of perivascular lymphocytes is seen.  The adjacent cerebral cortex shows distortion of the architecture with malorientation of the neurons, in keeping with focal cortical dysplasia.  The overall features are those of ganglioglioma. The Ki-67 index is less than 1%. Ganglioglioma with no anaplastic features is considered as Grade I in the 2007 WHO classification.

DIAGNOSIS: Brain tumour: Ganglioglioma (WHO grade I).

 

Six years post-diagnosis the patient remains seizure-free and with no evidence of disease recurrence. 

MRI

Left-sided craniotomy again noted together with the small area of left posterior temporal FLAIR hyperintensity at the site of resection. No suspicious enhancement elsewhere. No new findings. Stable disease with no evidence of recurrence.

Case Discussion

This is an example of left temporal ganglioglioma. Gangliogliomas are slow growing CNS neoplasms comprising of a mixture of neoplastic glial cells (primarily astocytes) and neoplastic ganglion cells (differentiated nerve cells), an in variable proportions1-5.

 

Gangliogliomas account for 0.4 to 7-6% of paediatric CNS neoplasms and approximately 1-3% of those in adults2. These tumors can occur anywhere in the neural-axis but are much more common in the brain than in the spinal cord1,2. The temporal lobe is the most common location of gangliogliomas, followed by, in order of descending frequency), cerebellum, parieto-occipital lobe, frontal lobe, and spinal cord6. These tumors have also been reported inthe brainstem, thalamus, hypothalamus, third and fourth ventricles, trigone of the lateral ventricle, pineal region, intrasellar region, and optic nerve4.

 

The most common clinical presentation is seizures, in particular, complex partial seizures, most likely a result of the high frequency of the temporal lobe location of these neoplasms1.

 

Although neuroradiological findings are not specific for gangliogliomas, the ability to diagnose this type of tumor greatly improved with the advent of CT and MRI. Common imaging findings of ganglioglioma on CT include1-6:

  • Calcification with an amorphous appearance
  • Subtle bony changes such as thinning of the calvarium
  • Isodensity, hypodensity, or a cystic appearance of the lesion
  • Contrast-enhancement of the solid non-calcified component of the lesion

Reported imaging characteristics on MRI include1-6:

  • Cystic appearance of the lesion
  • Hypointense on T1-weighted images
  • Hyperintense solid component on T2-weighted images, with variable signal in the cystic component

 

The principal form of treatment of ganglioglioma is surgical excision, with most lesions being amenable to complete resection1-6. Current literature suggests that radiation therapy is of minimal and/or questionable benefit, even in tumors which involve eloquent areas4. Most patients with preoperative seizures are seizure-free following total surgical resection1.

 

 

Case courtesy of Associate Professor Pramit Phal

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Case information

rID: 34304
Case created: 13th Feb 2015
Last edited: 8th Feb 2016
Inclusion in quiz mode: Included

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