Glioblastoma IDH wild-type
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Predominantly T2 hyperintense and T1 hypointense contiguous tumour expands the splenium and occipital radiations, surrounds the left lateral ventricular trigone occupying much of the left parieto-occipital lobes, and then extends anteroinferiorly into the left temporal lobe and left cerebral peduncle into the left pons.
There is minimal peripheral enhancement at the left cerebral peduncle however this is associated with more solid appearing diffusion restriction. More avid peripheral enhancement is seen around the more posterosuperior aspects of the tumour at the trigone and corpus callosum with associated patchy restricted diffusion.
Elevated cerebral blood volume is also seen at these peripherally enhancing margins. Abnormal enhancement also tracks along the ependymal lining of the left trigone and occipital horn. Within the left cerebral peduncle, there is elevation of choline and decrease in NAA in keeping with a tumour trace, while much of the left parieto-occipital component surrounding the left lateral ventricular trigone shows and elevation of lactate with an overall decrease in metabolites elsewhere compatible with necrosis.
Resultant compression of the trigone manifests in a trapped left occipital horn. Mild left to right subfalcine herniation of 4mm.
Conclusion: Findings compatible with extensive high grade glioma extending from the splenium of the corpus callosum to the left pons.
The patient went on to have a biopsy.
MICROSCOPIC DESCRIPTION: Sections show fragments of a moderately hypercellular astrocytic glioma. Tumour cells show moderate nuclear and cellular pleomorphism. Scattered mitotic figures are identified. There is prominent microvascular proliferation with multilayering of atypical cells around vessel lumena. Areas of palisaded tumour necrosis are also identified.
Immunohistochemistry results show tumour cells stain:
- GFAP Positive
- Nestin Positive (high)
- NogoA Negative
- IDH-1 R132H Negative (not mutated)
- ATRX Positive (not mutated)
- MGMT Negative (likely methylated)
- p53 Positive
- p16 CDKN2A Negative
- Topoisomerase labelling index: approximately 20-30%.
FINAL DIAGNOSIS: IDH-1 wild type Glioblastoma (WHO Grade IV).