Gemistocytic astrocytoma IDH mutant (WHO Grade II)

Case contributed by Heather Pascoe
Diagnosis almost certain


Atypical syncopal episode with features to suggest a possible seizure.

Patient Data

Age: 30 years
Gender: Female

No intracranial hemorrhage. Large region of hypodensity involving the right temporal lobe and extending into the inferior right frontal lobe. Local mass effect with sulcal effacement and partial effacement of the right lateral ventricle

In the medial right temporal lobe there is an ovoid 11 x 30 x 12 mm lesion with a thick enhancing rim. There is marked surrounding low attenuation on the non contrast CT consistent with edema. There is complete effacement of the temporal horn of the right lateral ventricle and partial effacement of the body and frontal horn. There is 2mm of leftward midline shift. No other abnormal contrast enhancement. Findings are suspicious for a primary brain tumor. Further evaluation with MRI recommended.

An enhancing mass lesion measuring 18 x 17 mm in the coronal plane, and 30 mm long in the right mesial temporal lobe, with another small anterior focus, is associated with a moderate amount of surrounding FLAIR hyperintensity that extends to involve cortex and amygdala. Posteriorly, it extends to the ventricular trigone, anteriorly to the posterior aspect of the inferior right frontal lobe, and superiorly to the right insula, internal and external capsules. Local mass effect, with sulcal effacement. The enhancement is associated with mild relative diffusion restriction. No susceptibility. Spectroscopy demonstrates elevated choline and probably also a small amount of lactate (noisy spectroscopy).

Findings are most in keeping with a primary right mesio-temporal tumor. GBM is favored, but also consider PXA and ganglioglioma.

Case Discussion

Biopsy results revealed a gemistocytic astrocytoma IDH mutant (WHO Grade II).

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