MACROSCOPY
The cut surface shows a homogeneous white rubbery appearance. No necrosis or haemorrhage are seen.
MICROSCOPY:
Sections show fragments of a well-circumscribed moderately hypercellular glioma. Focally tumour cells form papillae and perivascular rosettes with central hyalinised blood vessels. Tumour cells contain pale eosinophilic cytoplasm, oval nuclei with granular chromatin and inconspicuous nucleoli. Tumour cells demonstrate predominantly mild nuclear and cellular pleomorphism. Focally tumour cells show anaplastic features with enlarged, hyperchromatic nuclei and increased mitotic activity (up to 6/10hpf). No microvascular proliferation or pallisaded tumour necrosis are seen.
Immunohistochemistry results show tumour cells stain: GFAP Positive Nestin Positive (high) NogoA Negative IDH-1 R132H Negative (not mutated) ATRX Positive (not mutated) EMA Positive (perinuclear dot-like) CD99 Positive NeuN Negative Synaptophysin Negative CyclinD1 Positive STAT6 Negative CD20 Negative Topoisomerase labelling index: Approximately 15-20%. Comment: The histological and immunohistochemical features are considered most consistent with Astroblastoma.
The elevated mitotic count and high proliferation index both fulfill anaplastic criteria.