umls-concept:C0018923 | skos:definition | MSH: A rare malignant neoplasm characterized by rapidly proliferating, extensively infiltrating, anaplastic cells derived from blood vessels and lining irregular blood-filled or lumpy spaces. (Stedman, 25th ed),CSP: malignant neoplasm arising from vascular endothelial cells; the term may denote a specific histologic subtype, usually hemangiosarcoma, but also others such a lymphangiosarcoma or hemangiopericytoma.,NCI: A type of cancer that begins in the cells that line blood vessels.,NCI: A malignant vascular neoplasm arising from endothelial cells.,NCI: A malignant tumor composed of cells that recapitulate the morphologic and functional features of normal endothelium.,NCI: A malignant tumor arising from the endothelial cells of the blood vessels. Microscopically, it is characterized by frequently open vascular anastomosing and branching channels. The malignant cells that line the vascular channels are spindle or epithelioid and often display hyperchromatic nuclei. Angiosarcomas most frequently occur in the sk | lld:umls |