Anaplastic oligodendroglioma

Case contributed by Dr Ammar Ashraf


Headache, transient memory loss, and numbness in the right half of the body for more than 1 hour. History of a single episode of seizure. No history of fever, nausea/vomiting, or focal neurological deficit.

Patient Data

Age: 60 years
Gender: Male

A cortical/subcortical hypodensity (early ischemic insult Vs encephalitis) is seen in the left temporal lobe, which needs further evaluation. No recent intracranial hemorrhage, hydrocephalus, or mass effect/midline shift is seen.


Findings: Abnormal T2 and FLAIR hyperintense signal affecting the left temporal lobe & left insula, showing no diffusion restriction. Focal nonspecific white matter focus seen in the left centrum semiovale without any diffusion restriction. No recent infarction or intracranial hemorrhage is seen. The patient refused IV contrast.

Conclusion: T2 & FLAIR hyperintense signal in the left temporal lobe likely representing postictal changes. Other possible differentials like inflammatory or infectious causes are not excluded and further evaluation with a contrast-enhanced MRI brain is suggested.


5 months later

The patient lost to follow-up and 5 months later presented in our hospital emergency department with a history of seizures and slurred speech for 1 day.

Findings: Mildly enlarged left temporal lobe with a thickened and mildly hyperdense periphery and central hypodensity. The possibility of encephalitis, acute stroke, or an underlying mass lesion needs to be excluded. A few small cortical and subcortical hyper densities, suggestive of recent bleeds are seen in the left temporal lobe. Mild left-sided uncal herniation and minimal mass effect over the left lateral ventricle are noted; however, no significant midline shift is sen.


Findings: A space-occupying lesion measuring ~ 3 x 4 x 5 cm is seen in the left anterior temporal lobe. It has mixed solid & necrotic components, hemorrhagic components, and some areas of mild diffusion restriction. Solid components show moderate enhancement in the post-contrast study. Perilesional vasogenic edema, mild left-sided uncal herniation, and mild right-sided subfalcine herniation are noted. MRS shows reduced NAA and increased lactate-lipid peaks. M1 & M2 segments of the left MCA are closely adherent to the mass. Two other small faint non-enhancing focal lesions of indeterminate nature are seen in the left cerebral hemisphere (one in the left thalamus and the other in left corona radiata).

Impression: Aggressive looking left temporal lobe space-occupying lesion, suggestive of high-grade glioma; another possibility can be a metastatic lesion, which is, however, less likely.


6 weeks after debulking surgery

Status post left temporal craniotomy. Some mildly hyperdense foci (residual disease Vs post-operative changes) and vasogenic edema, are noted in the left temporal lobe. Interval improvement is appreciable in the mass effect and brain herniations noted on the previous study.

Case Discussion

Specimen source: Brain.

Pre-operative diagnosis:  Malignant primary brain tumor.

Procedure: Left temporal craniotomy & debulking of the tumor.

Diagnosis: Anaplastic oligodendroglioma (WHO grade III), IDH1 wild type.

Immunohistochemistry: The immunostains with the antibody anti-GFAP, Vimentin, and Olig2 are diffusely positive. ATRX is retained. P53 is negative. Ki67 is about 20%. IDH1 is negative.

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