PECAM1 and neoplasm: Thus, double staining of CD34+ PAS+ or CD31+ PAS+ vessels may represent sprouts of angiogenesis or blood vessels, whereas CD34− PAS+ or CD31−PAS+ tubes showed a pattern of vascularization as non-angiogenesis, named vasculogenic mimicry (VM), in which the tumor cells or non-endothelial cells formed vessels [14, 26].