MICROSCOPIC DESCRIPTION:
An H&E stained section demonstrates a moderately cellular tumour composed of elongated oval to wavy nuclei set within a fibrillary and myxoid stroma. There are scattered thin-walled blood vessels present. No necrosis or microvascular proliferation is seen. There are no mitoses identified. The Alcian blue stain confirms myxomatous tumour stroma. (Histology courtesy of Prof. Michael Gonzales)
Immunohistochemistry results show tumour cells stain:
- IDHl - negative.
- ATRX - positive.
- P53 - negative.
- H3K27M - negative.
- H3K27ME3 - positive.
- Topoisomerase proliferation index - 2-3%
FINAL DIAGNOSIS: Pilomyxoid astrocytoma (WHO grade I).