The patient went on to the dominant left parietal circumscribed lesion excised.
Sections show fragments of a moderately hypercellular astrocytic glioma with extensive microcyst formation. Tumour cells show moderate nuclear and cellular pleomorphism. Scattered mitotic figures are identified (up to 2 per 10hpf). No microvascular proliferation or necrosis are identified.
Immunohistochemistry results show tumour cells stain:
- GFAP Positive
- Nestin Positive (high)
- NogoA Positive
- IDH-1 R132H positive cytoplasmic staining = (mutated)
- ATRX loss of normal nuclear staining = Negative (mutated)
- MGMT loss of normal nuclear staining, except in endothelial cells of blood vessels (internal positive control) = Negative (likely methylated)
- p53 Positive p16 CDKN2A Positive
- Topoisomerase labelling index: 5%.
The infrequent mitoses and low Topoisomerase proliferation index (5%) favour a diagnosis of low-grade glioma (WHO II).
- FINAL DIAGNOSIS: IDH-1 mutant Diffuse Astrocytoma (WHO Grade II).
Histology courtesy of Dr Te Whiti Rogers