quantitative assessment and clinical relevance of vegfrspositive tumor cells in refractory brain tumors vascular endothelial growth factor vegfvegf receptor vegfr1 and 2 signaling is a potent activator of tumor angiogenesis although the expressions of vegfr1 and vegfr2 were initially thought to be limited to the endothelial cells it is now known that both the receptors are expressed in tumor cells this is the first study wherein vegfrspositive tumor cells are quantitatively evaluated for brain tumors with upregulated vegfvegfr signaling the percentage of vegfrspositive tumor cells was quantitatively evaluated in various brain tumors 10 glioblastomas 22 neurofibromatosis type 2 nf2related schwannomas 21 sporadic schwannomas 27 chordomas 36 meningiomas 29 hemangioblastomas 11 hemangiopericytoma and 13 ependymomas using immunohistochemistry vegfa expression was also analyzed using quantitative realtime polymerase chain reaction double immunofluorescence staining using antipdgfr and anticd34 antibody microvessel density and vessel diameter were analyzed to evaluate the vascular characteristics chordomas demonstrated an extremely higher percentage of vegfr1 and vegfr2positive tumor cells than other tumors in contrast meningiomas and hemangiopericytomas showed few vegfrspositive tumor cells the percentage of positive tumor cells in chordomas hemangioblastomas and nf2 schwannomas was associated with clinical courses such as shorter progression free survival and growth speed glioblastomas and nf2 schwannomas showed larger tumor vessels without pericyte coverage the present study is the first to quantitatively analyze vegfr1 and vegfr2 positive tumor cells in various types of refractory brain tumors this novel parameter significantly correlated with the progressive clinical courses