IMMUNOHISTOCHEMICAL DETECTION OF VASCULAR GROWTH-FACTORS IN ANGIOMATOUS AND ATYPICAL MENINGIOMAS, AS WELL AS HEMANGIOPERICYTOMAS

The arachnoideal compartment provides the vascular sources for three d ifferent tumor types rich in vessels: angiomatous meningioma, some aty pical meningioma with high vascularity and meningeal hemangiopericytom a. We investigated immunohistochemically the expression and distributi on of vascular mitogenes in 7 angiomatous meningiomas, 8 atypical meni ngiomas with high vasculature and 4 hemangiopericytomas. On the one ha nd it should be studied which vascular growth factors such as VPF/VEGF -1, VPF/VEGF-2, bFGF, PDGF and TGF-alpha could be responsible for the close meshwork of vessels within the tumors. On the other hand we were interested in whether or not there are differences in vascular mitoge ns between slowly growing angiomatous meningiomas and both other types with their increased tendency to recur. PDGF and TGF-alpha were exten sively expressed in the endothelium and smooth muscle cells of the ves sels, as well as tumor cells. VEGF-2 could only be found in endothelia l cells of all three tumor entities. bFGF was localized in some vessel s of angiomatous meningiomas and VEGF-1 revealed a very low expression with a localization comparable with VEGF-2. Moreover, uPAR was diffus ely expressed in nearly all tumor cells and endothelial cells. The fac t that tumor cells of hemangiopericytomas and meningiomas did not show any immunohistochemical reaction with VEGF's could indicate a lower p riority of these growth factors for neovascularization in this type of neoplasm. A different expression of vascular mitogens between benign angiomatous meningiomas and atypical meningiomas as well as hemangiope ricytomas with their tendency for recurrence could not be observed. Th e morphological evidence for extravasates of IgG-proteins, Fibrin and Fibronectin due to VPF-effects seems not to be a renouncable condition for neoangiogensis in the tumors investigated.