The sections show replacement of cerebellar parenchyma by a moderately hypercellular, intensely vascular tumour. Vascular channels vary from large calibre thin-walled sinusoids to small capillaries. These are lined by unremarkable endothelial cells.
Intervening tumour is composed of lobules and diffuse sheets of stromal cells with round and oval vesicular nuclei and a variable amount of pale and granular cytoplasm. No mitotic figures are identified and there is no vascular endothelial cell hyperplasia and no necrosis. The features are of a capillary haemangioblastoma.
DIAGNOSIS: Posterior fossa capillary haemangioblastoma (WHO Grade I)