HIF1A and hemangioma: The pathophysiological mechanism leading to hemangioma development in this peculiar site is still unclear, but it is known that an hypoxic environment, such as the one in the relatively poorly vascularized gallbladder fundus, may lead to an upregulation of hypoxia inducible factor-1α (HIF-1α)-responsive chemokines such as stromal cell derived factor-1α (SDF-1α) and vascular endothelial growth factors (VEGF), both of which promote the recruitment and proliferation of endothelial progenitor cells [22].