A sarcoma is a rare kind of cancer. Sarcomas grow in connective tissue -- cells that connect or support other kinds of tissue in your body. These tumours are most common in the bones, muscles, tendons, cartilage, nerves, fat, and blood vessels of your arms and legs, but they can also happen in other areas of your body. Although there are more than 50 types of sarcoma, they can be grouped into two main kinds: soft tissue sarcoma and bone sarcoma, or osteosarcoma. It is made up of many “subtypes” because it can arise from a variety of tissue structures. Because these tissues are found everywhere on the body, Sarcomas can arise anywhere.