MICROSCOPIC DESCRIPTION: The section shows a moderately hypercellular tumour. This consists of elongated spindle cells, interspersed with collagen fibres and with a fascicular and storiform architectural arrangement. A single small aggregate of meningothelial cells is noted. The spindled tumour cells show mild nuclear pleomorphism. No mitotic figures or areas of necrosis are identified and there is no evidence of brain invasion. Attachment to dura is noted. Dural margins are clear of tumour. Immunohistochemistry shows strong diffuse staining for CD34 and moderately strong staining for bcl-2 in spindled tumour cells. There is weak staining for epithelial membrane antigen (EMA). No staining for ALK-1 or progesterone receptor (PgR) is seen. The features are of solitary fibrous tumour (WHO Grade II). The topoisomerase labelling index is approximately 2%.
DIAGNOSIS: Brain tumour: Solitary fibrous tumour (WHO Grade II).