In this study, the expression levels of the embryonic stem cell reprogramming factors Oct4, Nanog, Myc, Sox2, and Klf4 were examined via immunohistochemistry in a panel of 71 benign, borderline, and malignant vascular tumors including capillary hemangioma, cavernous hemangioma, granulomatous hemangioma, venous hemangioma, hemangioendothelioma, hemangiopericytoma, and angiosarcoma. This evidence concerns the gene POU5F1 and vascular neoplasm.