Diffuse fibrillary astrocytoma
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The anterior temporal lobe demonstrates diffuse increased T2 signal involving both white and grey matter, with extension into the insular cortex, and inferior frontal lobe, as well as posteriorly along the hippocampal tail. There in no abnormal enhancement, restricted diffusion or evidence of calcification / haemorrhage.
Features are almost certainly those of a diffuse astrocytoma, with appearances most consistent with fibrillary subtype.
The patient went on to have a biopsy, confirming the diagnosis.
The sections show fragments of cerebral cortex and white matter. A portion of hippocampus is included in specimen 4. In all specimens, the white matter shows moderate hypercellularity and the cortex shows prominent perineuronal secondary structuring by atypical fibrillary astrocytes. Moderate numbers of mature neurones are identified in white matter. No mitotic figures are identified. There is no microvascular proliferation and no necrosis is seen. The topoisomerase labelling index is approximately 3%.
- GFAP positive
- IDH-1 R132H negative (not mutated)
- ATRX positive (not mutated)
- MGMT positive (likely unmethylated)
- p53 positive
- p16 negative
Diffuse fibrillary astrocytoma (WHO Grade II)