A usually aggressive malignant neoplasm of the soft tissue or bone. It arises from muscle, fat, fibrous tissue, bone, cartilage, and blood vessels. Sarcomas occur in both children and adults. The prognosis depends largely on the degree of differentiation (grade) of the neoplasm. Representative subtypes are liposarcoma, leiomyosarcoma, osteosarcoma, and chondrosarcoma.