vWF is used as a marker for

Ans. A. AngiosarcomaExplanationThe vWF is the least sensitive of the vascular markers and is positive in 50% to 75% of vascular tumors.von Willebrand factor (vWF):It is a glycoprotein produced uniquely by endothelial cells and megakaryocytes, is routinely used to identify vessels in tissue sections.Vessel density in tumor specimens, as determined by immuno-histochemical staining for vWF or other endothelial cell markers, is a negative prognostic factor for many solid tumors.vWF is heterogeneously distributed throughout the vasculature, transcriptional control in response to the tissue microenvironment being responsible for local variations in endothelial cell levels of vWF.Fibroblast growth factor-2 and vascular endothelial growth factor, potent angiogenesis inducers expressed in a variety of tumors, up-regulate expression of vWF mRNA and protein in cultured endothelial cells with a synergistic effect.Measurement of vWF mRNA in tumors detect activated endothelium or angiogenesis.