Paraffin sections show a moderately hypercellular glial tumour. Tumour cells have uniform round and ovoid nuclei with a granular arrangement of chromatin and a variable amount of pale to clear cytoplasm. These are arranged in prominent perivascular pseudorosettes as well as diffuse sheets. No mitotic figures are identified. A single small focus of vascular endothelial cell hyperpklasia is noted in one fragment. There is no necrosis. Large calibre intensely congested vascular channels are present in separate fragments. The majority of tumour cells show prominent perinuclear dot immunostaining for epithelial membrane antigen (EMA) typical of ependymal cells. There is also patchy immunostaining for GFAP. The features are of ependymoma. The topoisomerase labelling index is <1%.
DIAGNOSIS: Left frontal and lateral ventricle tumour: Ependymoma (WHO Grade II).