Cancer of the bone and joint.

The bones and joints are skeletal structures derived from the mesoderm, and cancers arising fiom them belong to the general class of malignant tumors designated as sarcomas. However, when the cancer is composed of a specific tissue or cell of the skeletal structure the name of that tissue or cell may comprise a part of the name of the tumor. Primary cancer of the bone differs so widely from primary cancer of the joint that the two lesions call for separate consideration. CANCER OF THE BONE Sarcoma of the Bone.— Sarcoma arises more frequently in the bone than in any other tissue or system of the body, and the frequency with which it is responsible for loss of limb or life makes it rank as the major problem of malignant tumors springing from the mesoblastic tissues. However, the relative incidence of sarcoma of the bone is extremely low in comparison