Case contributed by Frank Gaillard



Patient Data

Age: 25 years
Gender: Female

A mass in the left frontal lobe is present, predominantly of low attenuation but with areas of calcific density. Features are most consistent with an oligodendroglioma. 


Left frontal lobe intra-axial lesion is demonstrated that involves cortex as well as subcortical white matter, expanding both, with moderate regional mass effect, compressing the frontal horns of the lateral ventricles and effacing regional sulci. Bowing of the anterior aspect of the falx cerebri approximately 7.5 mm to the right. No hydrocephalus. Scattered within the tumor are small nodular areas of contrast enhancement, particularly at the medial aspect and at the rim, with no discrete mass enhancing mass demonstrated. The rim of the tumor also demonstrates restricted diffusion (ADC 600-800 x 10^-6 mm^2/s). There are areas of susceptibility artefact within and surrounding the tumor, some representing products of blood degradation. A small amount of calcification is probably also present within the lesion. The contrast enhancing components show increased rCBV, again more noticeably at the medial aspect. MRS through the enhancing components also shows increased choline, increased lipid/lactate and slightly reduced NAA. There are also multiple prominent vessels seen traversing the tumor, felt to be sulcal. Surrounding T2 FLAIR hyperintensity in the left frontal lobe. 

Features are those of an oligodendroglioma


MICROSCOPIC DESCRIPTION: Paraffin sections show a densely cellular glial tumor. Tumor cells have oligodendroglial morphological features - round and oval nuclei with vesicular chromatin and perinuclear clearing with tumor cells arranged in lobules delimited by thin-walled capillaries. A very occasional mitotic figure is identified. There is no multilayering of atypical cells around vessel Iumena and no necrosis is identified. There is patchy tumor calcification. Tumor extends through the full thickness of cerebral cortex, breaches the pia-arachnoid and extends into the sub-arachnoid space.


GFAP negative in tumor cells NogoA positive IDH-1 R132H positive (mutated) ATRX positive (not mutated) P53 positive P16 CDK NZA positive Topoisomerase labeling index: Approximately 10%

FISH for chromosome 1p/19q deletion:

  • Chromosome 1. Mean copies 1p per cell: 1.40 Mean copies 1q per cell: 2.17 1p/1q ratio: 0.65 Interpretation: 1p loss detected by FISH
  • Chromosome 19 Mean copies 19q per cell: 1.13 Mean copies 19p per cell: 1.88 19q/19p ratio: 0.60 Interpretation: 19q loss detected by FISH

FINAL DIAGNOSIS: Oligodendroglioma (WHO Grade II)

Case Discussion

This is a good example of an oligodendroglioma with appropriate molecular phenotype (IDH mutant chromosome 1p/19q co-deleted) required for the diagnosis as required by the current (2016) WHO classification of CNS tumors.

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