Gemistocytic astrocytoma, IDH1 mutant (WHO Grade II).
Sections show a moderately cellular tumour composed of moderately pleomorphic cells containing round to oval, hyperchromatic nuclei with inconspicuous nucleoli and abundant dense eosinophilic cytoplasm. Cells are arranged in diffuse sheets demonstrating focal perineuronal satellitosis. Occasional mitotic figures are identified (up to 1/20hpf). No necrosis or microvascular proliferation is seen.
GFAP positive
IDH-1 R132H postiive
ATRX positive (non-mutated)
p53 positive
p16 negative
Topoisomerase index 5%