The process leading to a misdiagnosis of malignant vascular tumor, particularly composite hemangioendothelioma, a vascular tumor composed of a complex admixture of histologically benign and malignant vascular components, is ameliorated by the complex morphology and immunohistochemical expressions of CD31, CD34, ERG, and Factor VIII, largely known as vascular/endothelial markers [14]. This evidence concerns the gene ERG and vascular cancer.