A benign (not cancer) tumor that has both bone and cartilage in it. This type of tumor usually occurs at the ends of the long bones of the arms and legs or in the pelvis or shoulder. It may cause abnormal growth of the arms, hands, and legs; problems moving the joints; and pain, numbness, and tingling. There may be one or more tumors, and having multiple tumors runs in families. Osteochondromas may also occur at some point in time after cancer treatment, such as stem cell transplant.