MICROSCOPIC DESCRIPTION: Paraffin sections show a moderately hypercellular, intensely vascular tumour. This is composed of cells with moderately pleomorphic round oval and angulated hyperchromatic nuclei and a variable amount of pale and foamy cytoplasm. These are arranged in diffuse sheets as well as lobules which are enclosed by thin-walled capillaries. Vascular spaces vary from large calibre thin-walled sinusoidal structures to capillaries. A very occasional mitotic figure is identified in tumour cells. No areas of necrosis are seen. Tumour is attached to dense collagenous tissue consistent with meninges.
Immunohistochemistry shows strong staining of vascular endothelium for CD34. No reactivity for GFAP, CD34 or cytokeratrin AE1/AE3 is seen in tumour cells. The features are of capillary haemangioblastoma.
FINAL DIAGNOSIS: Capillary haemangioblastoma.
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