Sarcomata  are the most common tumors of bone; they are malignant, and when removed, tend to recur, either locally or by metastasis, in different parts of the body. The metastases usually are distributed by the circulation.

These tumors may arise from the marrow, but generally in the epiphysis of the bone and extend to the shaft only at a later stage of their development. As the tumor advances, it causes a softening and an absorption of the original cellular marrow until it approaches the periosteum.

In many cases the periosteum, as about any form of foreign body, then begins to proliferate and forms a shell of periosteal bone surrounding the tumor. In that way the shell of the bone oftentimes becomes very much enlargedbefore there is any extension of the process through the shell to the adjacent tissue. By destruction of the marrow and of the cortex, great softening of the bone may occur so that spontaneous fractures not infrequently are seen.

Other sarcomata arise from the periosteum, and usually originate from one side of the bone, although occasionally they entirely surround the bone. In the periosteal sarcomata, a new formation of bone is common and the bone is frequently arranged in a radical way, giving a most remarkable picture on the X-ray plate.