Diffuse astrocytoma IDH-mutant
Presentation
Left sided weakness.
Patient Data
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A large region of low attenuation with mass effect and no enhancement involves primarily the right parietal lobe, including the cortex. No calcification.
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Large left parietal mass with extensive cortical involvement, elevated choline and extension into the corpus callosum. No convincing enhancement. CBV is elevated.
Conclusion:
Features are those of a primary brain tumour. Extensive cortical involvement favours an oligodendroglial component.
Case Discussion
The patient went on to have surgery.
Histology
MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a mildy hypercellular glial tumour. This consists predominantly of oligodendroglial cells which show mild nuclear pleomorphism. These are admixed with a quantitatively smaller population of atypical astrocytic cells. Scattered gliofibrillary oligodendrocytes are also noted and there is patchy reactive astrocytic gliosis. No mitotic figures are identified. There is no microvascular proliferation and no necrosis is identified.
IMMUNOHISTOCHEMISTRY:
- GFAP positive in tumour and reactive astrocytes and in gliofibrillary oligodendrocytes.
- Nogo A positive in tumour oligodendrocytes
- IDH-1 R132H positive (mutated)
- MGMT positive (likely unmethylated).
- p53 positive.
- p16 positive.
- FISH for chromosome 1p/19q deletion:
- 1p36: No loss detected
- 19q13: No loss detected
Topoisomerase labelling index: Approximately 8%.
FINAL DIAGNOSIS: Astrocytoma (WHO Grade II)
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