1. "Brain tissue": Fragments of soft gelatinous tissue up to 3mm. Portion for frozen section/smear. Remaining tissue for formalin plus glutaraldehyde (hold for EM).
2. "Brain tissue": Multiple pieces of soft tan tissue 17x15x3mm in aggregate. A1.
1&2. Paraffin sections show a moderately hypercellular tumour. Tumour cells have uniform medium sized round nuclei with granular chromatin and delicate processes and are arranged on lobules and solid sheets in a neuropil-like background. Scattered cells are undergoing apoptosis. No mitotic figures are identified. Small capillaries are prominent throughout the tumour but no multilayering of atypical cells around vessel lumena is seen. There is no necrosis.
Immunohistochemistry shows that tumour cells are positive for synaptophysin and NeuN. GFAP and tyrosinase are negative.
The features are of central neurocytoma (WHO Grade II).
"Intraventricular tumour": Central neurocytoma (WHO Grade II).