Exostosis bursata. (Orlow.)
When otherwise, complete removal with careful cauterization of the base of the growth or surface from which it sprang will usually be sufficient. These cartilaginous tumors tend on one hand to mucoid softening and cystic formation, and on the other to calcification or ossification, by which the original cartilaginous character of the growth may be concealed.
Osteomas.
—Osteomas are by some writers made to include exostoses and hyperostoses. In accordance with the system followed in this work only those growths are considered as tumors which are of no physiological usefulness, and it is preferable to maintain a distinction between osteomas and the exostoses or bone hypertrophies, which pertain either to evolutionary relics or to constitutional affections.
There is, however, a peculiar form of exostosis which becomes covered by an adventitious bursa, whose walls become in time quite thick, which is called exostosis bursata. In the cavity of this bursa may frequently be found rice-grain or other fibrinous concretions. This lesion is common in the neighborhood of joints, and the new bursa frequently communicates with the joint cavity ([Fig. 249]).
Myxomas.
—Myxomas are rare in bone, and are seen usually only as degenerated forms of cartilaginous bony or malignant growths. They lead to cystic degeneration. A primary growth of this kind has for its origin the bone-marrow.
Sarcoma.
—As already described, sarcoma of bone should not be confused with osteosarcoma. (See [Sarcoma].) The former refers to sarcoma springing from the true osseous tissue or periosteum. When central the bony walls are expanded and form a shell. Osteosarcoma refers to a tumor springing from the original connective tissue which holds the bony elements together, and contains osseous tissue scattered through it. Sarcoma occurs usually in the long bones, although none are exempt; mostly single, it nevertheless may be multiple. It occurs frequently in the young, is seen even at birth, and in these instances is supposed to take its origin usually from epiphyseal structures. No period of life is, however, exempt. Tumors attain sometimes enormous size. Marsh has recently described such a tumor weighing thirty-three pounds. Microscopically these tumors may assume any of the varieties, endothelioma, angiosarcoma, etc., those of the most rapid growth being found rather of the round-cell type, while those of slow growth are usually myeloid or contain giant cells.