March 2010 Archives

Hemangioblastoma

This patient presented in his 20s with 2 months of progressive headaches and was found to have a right cerebellar cystic mass.

20x
hemantioblast20x1.jpg

40x

hemangio40x1.jpg


Hemangioblastoma (WHO grade I): 
"Uncertain" Histogenesis

      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).


Clinical Features

- 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



Histopathology

- 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

-Rare mitosis

-Cyst wall may show reacive astrocytosis with Rosenthal Fibers



Immunohistochemistry

-Stromal cells are positive for: Vimentin,S100,Oil Red O

-Stromal cells are negative for :CD34,FVIII,CK,EMA,GFAP


DDX

-Metastatic Renal Cell CA: Non-cystic,Abundant mitosis,EMA,Vimentin and CK  positive

-Pilocytic Astrocytoma: Fibrillary astrocytes, GFAP diffusely positive



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