Diffuse astrocytoma: protoplasmic and gemistocytic components

Case contributed by A.Prof Frank Gaillard

Presentation

Seizures.

Patient Data

Age: 35-40 years
Gender: Female

A left frontal lobe mass, which involves the superior frontal gyrus cortex and subjacent white matter, demonstrates high T2 and low T1 signal, with some areas of partial FLAIR suppression. Within the centre of the lesion, corresponding to the areas of increased CT density, is irregular intrinsic high T1 material, with some signal loss on EPI suggestive of blood product. There is no significant restricted diffusion, and no elevated CBV. No convincing contrast enhancement. MRS demonstrates high myo-inositol, increased choline and somewhat depressed NAA. No lactate.

Slight high sulcal signal on FLAIR is attributable to the patient being intubated. The remainder of the brain is unremarkable. No abnormal vessels on MRA.

Conclusion:

Features are those of a primary brain tumour. MRS, perfusion and morphology suggest a low (WHO II) or perhaps intermediate (WHO III) grade glioma with non-fibrillary components (e.g. gemistocytic, protoplasmic or oligodendroglial component).

Case Discussion

The patient went on to have a craniotomy. 

Histology

MICROSCOPIC DESCRIPTION:

The sections show features of a moderately cellular astrocytic tumour. The tumour cells are mainly of the protoplasmic type. They have mildly enlarged round nuclei with short cytoplasmic processes. Scattered gemistocytes are noted, occupying less than 10% of the cell population. Prominent microcystic change is seen in the background.

Tumour cells extend into the cerebral cortex. Mitoses are inconspicuous. No microvascular proliferation or necrosis is present. The features are those of diffuse astrocytoma of predominantly the protoplasmic type. The tumour cells are p53 and p16 positive. The topoisomerase index is 1%. They are IDH-1 and MGMT immunostains negative.

FINAL DIAGNOSIS:

Diffuse astrocytoma (WHO Grade II) - mixed protoplasmic and gemistocytic. 

 

Until recently, protoplasmic astrocytomas were classified as a subtype low-grade astrocytoma, however, in the latest (2016) update to WHO classification of CNS tumours, protoplasmic astrocytomas no longer exists as a distinct entity. 

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Case Information

rID: 34582
Case created: 27th Feb 2015
Last edited: 21st Jul 2016
Inclusion in quiz mode: Included

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