Brain, Hemangioblastoma

Based on WHO classification of the CNS, hemangioblastoma is a grade I benign slow-growing tumour of small blood vessels and associated stroma. It typically occurs in in the brain stem, cerebellum, and spinal cord of adults. Most cases are sporadic (70%); however, others are associated with von Hippel-Lindau (VHL) disease (30%). On imaging, hemangioblastomas are often multicystic, highly-vascularized, and well demarcated from the surrounding tissue. Morphologically it is characterized with two components: 1) tumour stromal cells that are vacuolated with lipid droplets and considerable nuclear atypia, and 2) highly vascularized network. The tumour stromal cells are positive for inhibin. In some cases, this appearance can mimic metastatic renal cell carcinoma, which can be excluded by immunohistochemistry and clinical correlation.