Masses left behind by healed tissue after a fracture or by certain diseases such as bone tumors are called skeletal masses. The skeletal system, like other organs, can develop tumors from any tissue component or metastatic lesions from other organs. Tumors that invade the bone can occur in the bone cells, the hematopoietic component of the bone, the cartilage, and the fibrous or synovial component. Other tumors may arise from the muscles and nerves, blood vessels, and fatty tissue of the bone. Bone masses may not be felt at first, but when they are larger, they may be swollen and painful to the touch. The causes are various, and are commonly found in the following two types: 1. lumps left by healing tissue after fracture. 2. 2. Various bone tumors or tumors metastasizing to the bone, such as myeloma, bone cancer, etc. Symptoms and signs: Pain in the affected area, localized lumps and swelling in the joints and limbs. Restricted movement of the affected joints and limbs. Most of them are found in flat bones, especially in the sternum, ribs, skull, clavicle, and mandible, etc. Local bones are elevated, hard to touch or rubbery and soft to the touch. Tumor tissue commonly infiltrates nearby soft tissues, and bead-like changes at the junction of the sternum, ribs, and jawbone are seen in half of the patients.