Immunohistochemical detection of factor VIII/von willebrand factor in hyperplastic endothelial cells in glioblastoma multiforme and mixed glioma-sarcoma

The sarcomatous components of most glioma-sarcomas are thought to arise from the neoplastic transformation of hyperplastic endothelial and adventitial vascular cells in a preexisting glioblastoma multiforme. The expression of factor VIII/von Willebrand factor (FVIII/vWF), a marker for endothelial cells, and of glial fibrillary acidic protein (GFAP), a marker for glial cells, was examined in 10 glioblastomas and seven mixed glioma-sarcomas using the peroxidase-antiperoxidase immunohistochemical technique. Hyperplasia of small blood vessels was observed in all 10 glioblastomas; in five, the vascular proliferation had resulted in the formation of prominent glomeruloid structures. FVIII/vWF was detected in the endothelial cells in these vascular structures, but not in the adventitial cells. In the mixed glioma-sarcomas, FVIII/vWF was detected only in endothelial cells; there was no staining for FVIII/vWF in the neoplastic mesenchymal cells. The gliomatous components of the mixed tumors stained intensely for GFAP. These observations indicate that both endothelial and nonendothelial cell types contribute to the small vessel hyperplasia in glioblastomas, and that the sarcomatous components of mixed glioma-sarcomas are derived from either non-endothelial cells or endothelial cells that have undergone antigenic loss following transformation.