Vascular endothelial growth factor expression, vascularization and proliferation in paragangliomas

Paragangliomas are heavily vascularized tumors, and the expression of VEGF (vascular endothelial growth factor) has been reported. The aim of our study was to extend the available database of VEGF expression in paraganglioma, to add correlated data concerning vessel density and proliferative activity, and to draw conclusions concerning the mechanisms resulting in tumor vascularization and growth.

Semiquantitative histopathologic examination of paraganglioma specimens obtained from surgical cases.

Paraffin-embedded paragangliomas were analyzed by immunohistochemistry. Fourteen consecutive samples were hybridized with VEGF-, CD31- and Ki67-specific antibodies, and visualized by diaminobenzidine staining. Vessel density was determined by counting CD31-positive vessels and proliferation by quantification of Ki67-positive cells.

Ten out of 14 samples were positive for VEGF. In this group, vessel density was up to 5 times as high and proliferative activity was about twice as high as in the VEGF-negative group.

We observed higher CD31 and Ki67 counts in VEGF-positive tumors, but statistical significance could not be assessed due to low sample numbers. These data might suggest a contribution of VEGF secreted by paragangliomas to tumor vascularization and possibly proliferation. The clinical impact of VEGF expression analysis has to be proven in future studies.