MICROSCOPIC DESCRIPTION: 1-2. Sections show fragments of a hypercellular tumour composed of cells demonstrating moderate nuclear pleomorphism. Focally tumour cells show an elongate, plump spindle cell morphology with a fascicular arrangement. Large pleomorphic tumour cells with foamy cytoplasm and multinucleated floret cells are present. Eosinophilic granular bodies and aggregates of perivascular lymphocytes are identified. No neuronal tumour cell component is seen. Occasional mitotic figures are identified (up to 3 per 50hpf). No microvascular proliferation or pallisaded tumour necrosis are seen.
Immunohistochemistry results show tumour cells stain:
- GFAP Positive
- Nestin Positive
- NogoA Negative
- IDH-1 R132H Negative (not mutated)
- ATRX Positive (not mutated)
- MGMT Positive (likely not methylated)
- p53 Positive
- p16 CDKN2A Positive
- B-tubulin Positive
- Topoisomerase labelling index: Approximately 8%.
DIAGNOSIS: 1-2. Brain tissue: Pleomorphic Xanthoastrocytoma (WHO Grade II).