Paraffin sections show an intensely vascular moderately hypercellular tumor within cerebellum. Vascular spaces vary from large thin-walled sinusoidal structures down to thin-walled capillaries. The latter enclose lobules of cells with uniform round and oval vesicular nuclei and a variable amount of foamy cytoplasm. No mitotic figures or areas of necrosis are identified. Immunohistochemistry shows patchy moderately strong staining in tumor cells for Inhibin. No staining for CD10 or cytokeratins CAM5.2 or AE1/AE3 is seen in tumor cells. The features are of cerebellar capillary hemangioblastoma.
FINAL DIAGNOSIS: Right CP angle lesion: Capillary hemangioblastoma (WHO Grade 1).