Ewing sarcoma is a rare type of cancer that occurs in bones or in the soft tissue around the bones. Usually, it begins in the long bones of the pelvis, legs or arms. It can also occur in any bone. In some cases, Ewing sarcoma starts in the soft tissues of the arms, legs, abdomen or other locations.
The cause of Ewing sarcoma is unknown. Although Ewing sarcoma arises from specific types of cells, it doesn't appear to be inherited.