Chondroblastoma A chondroblastoma is a rare type of benign bone tumor that originates from cartilage. Enchondroma Enchondromas are the most common type of hand tumor. Although they may affect people of any age, they are most common between ages 10 and 20. Giant Cell Tumor Giant cell tumors most often appear in the knee, but they can also involve the bones of the arms and the legs, or the flat bones such as the breastbone or pelvis. Osteochondroma Osteochondroma is an overgrowth of cartilage and bone near the end of the bone near the growth plate. Chondrosarcoma Chondrosarcoma is a malignant type of bone cancer that primarily affects the cartilage cells of the femur, arm, pelvis, knee, and spine. Ewing Sarcoma in Adults Ewing sarcoma can occur in any bone, but is most often found in the extremities and can involve muscle and the soft tissues around the tumor site. Multiple Myeloma Myeloma bone disease is cancer that affects certain white blood cells called plasma cells. Osteosarcoma Osteosarcoma usually affects the long bones around the knee. It occurs most often in children, adolescents, and young adults.