Hemangioblastoma (WHO grade I):
• Various cell lineages such as vascular, glial, neural, fibrohistiocytic, and smooth muscle/myofibroblastic have been proposed for the so-called stromal cells, which are thought to represent the neoplastic component of these lesions
- Neg for endothelial markers
- CD133, VEGF positive, Epo/EpoR coexpression'
- GFAP positive cells may result from phagocytosis
• The VHL gene is expressed particularly in Purkinje cells of the cerebellum (mutations may be inherited or somatic).
• VHL mutation may lead to developmental arrest of angioblasts. Pluripotent neoplastic angioblasts may be the cell of origin.
• Possible origin is 'angiomesenchyme' which may give rise to three cell types (stromal cells, pericytes, and endothelial cells).
- 25 % occur in VHL Patients, 75 % occur sporadicly
- Locations : Cerebellum , brain stem,Spinal cord, Supretentorial sites more frequently in VHL patients
-Symptoms are associated with increased ICP, Secondary erythrocytosis secondary to EPO production
-MRI shows cystic lesion with enhancement
- Tumors consisting of numerous vessels intermixed with stromal cells
- Vessels have hyperplastic endothelial cells and pericytes
- Stromal cells have abundant lipid-rich clear cytoplasm with slight pleomorphic nuclei
-Cyst wall may show reacive astrocytosis with Rosenthal Fibers
-Stromal cells are positive for: Vimentin,S100,Oil Red O
-Stromal cells are negative for :CD34,FVIII,CK,EMA,GFAP
-Metastatic Renal Cell CA: Non-cystic,Abundant mitosis,EMA,Vimentin and CK positive
-Pilocytic Astrocytoma: Fibrillary astrocytes, GFAP diffusely positive