Gemistocytic astrocytoma

Case contributed by David Mitchell
Diagnosis certain


First episode of seizure.

Patient Data

Age: 50
Gender: Male

7.1 x 3.2 cm nonenhancing lesion within the left frontoparietal region.


Large left frontoparietal nonenhancing tumor involving the corpus callosum, grey and white matter. There are several intratumoral microcysts. The tumor demonstrates high ADC values. No regions of elevated CBV. Spectroscopy (not shown) demonstrates increased choline and reduced NAA but no regions of high lactate peak.


Gemistocytic astrocytoma, IDH1 mutant (WHO Grade II).

Sections show a moderately cellular tumor composed of moderately pleomorphic cells containing round to oval, hyperchromatic nuclei with inconspicuous nucleoli and abundant dense eosinophilic cytoplasm. Cells are arranged in diffuse sheets demonstrating focal perineuronal satellitosis.  Occasional mitotic figures are identified (up to 1/20hpf).  No necrosis or microvascular proliferation is seen.

GFAP positive

IDH-1 R132H postiive

ATRX positive (non-mutated)

p53 positive

p16 negative

Topoisomerase index 5%


Case Discussion

In this age-group, a diffuse glioma is most likely to have an IDH1 or IDH2 mutation. The small internal foci of FLAIR suppression and lack of elevated CBV could suggest intact 1p19q.

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