3. Nodes growing peripherally: (a) primary sarcoma; (b) primary carcinoma.
4. Cysts: (a) retention; (b) extravasa tion; (c) exudation [as ovarian and parovarian]; (d) softening; (e) para sitic; (f) dermoid.
When on the surface they appear as: 1. Flat tabular swelling: (a) keloid; (b) angioma; (c) lymphangioma; (d) squamous epithelioma; (e) cholesteatoma; (f) sarcoma of serous membranes.
2. Tubers (a partly projecting node): (a) osteoma; (b) chondroma; (c) osteo chondroma; (d) giant-cell sarcoma.
3. Fungi (fungus Inematoides): (a) soft cancer; (b) telangiectatic sarcoma; (c) cavernous angioma.
4. Polyps: (a) myxoma; (b) soft fi broma; (c) lipoma; (d) adenoma; (e) sarcoma of serous sacs.
5. Dendritic: (a) warts; (b) papilloma; (c) epithelioma.
G. Papillw: (a) horns; (b) corns; (c) condyloma.
It is at times impossible from micro scopical study alone to tell a sarcoma from granulating tissue. In one well known case the ulcerating area of a lipoma was diagnosed as malignant, the leg was amputated, and death resulted. We cannot always distinguish sarcoma, such as an endothelioma, from a cancer, an adenocarcinoma from an adenoma, or an adenoma from an hyperplastic gland ular structure.
Etiology.-1. A first group of tumors may be regarded as being composed of congenital deposits of tissue in an abnor mal situation or of rests of tissue which do not disappear in the course of devel opment (Cohnheim's theory). These patches are usually present at birth and develop in later life. To this group be long many varieties of osteoma, chon drama, angioma, lipoma, fibroma, sar coma, adenoma, cysts, and teratoid tu mors. The latter may originate in a transposition of tissue-cells, in the im plantation of a rudimentary portion of a twin, or in the pathological growth of male or female cells of generation.
Osteoma is, for the most part, to be explained on embryonal grounds (Cohn heim). It is often seen as an exostosis in the neighborhood of an epiphysis or as an ossification of some cartilaginous "rest"; in many other cases it is the result of traumatic osteoperiostitis. or of syphilis or rachitis.
Chondroma is most common in infancy and childhood, and its consideration is practically inseparable from that of rickets. Such cartilaginous tumors as
are not to be explained as expressions of rachitis are to be regarded as inclu sions, according to the embryonal theory of Cohnheim. Roswell Park (Amer. Jour. Med. Sci.. May, 'OS).
2. From 14 to 17 per cent. of all tu mors arise after an injury, though, no doubt, some of these eases owe their de velopment to the irritation by the trau matism of embryonal rests pre-existing in the body. Out of one hundred and seventy cases of sarcoma collected by Coley (Annals of Surg., Sept., '97), 27 per cent. gave a history of trauma; in one case the tumor appeared within a week after the injury. Such a ease raises an interesting question as to the liability of an accident insurance company. While Coroner's Physician of Philadelphia a body came to me for autopsy in which there was doubt as to whether a kick might have given rise to a cancer of the large intestine (\Tirchow's theory).
Analysis of 714 eases, embracing be nign and malign growths. But 10 could with more or less certainty be traced to an antecedent trauma. If the "probable" eases were added the proportion could be placed at 5 per cent.
Most benign growths originated with out any causal connection with trauma. In osteornas, however, no less than 40 per cent. were traceable to a severe in jury; yet even under these circum stances the underlying cause may have been an osteomyelitis, tubercular or syphilitic, or even an attenuated bacil lary infection. Sarcoma due to trauma is represented by 7 per cent., while car cinoma figures with but 1 per cent., the injuries having never been of a severe nature. Statistically, traumatism is an etiological factor only in ostcomas, car cinomas, and sarcomas. K. Wnrz (Bei zur klin. Chir., 13. 26, II. 3, 1900).
3. Tumors follow inflammations, espe cially ulcers which have resulted in ex tensive cicatrization. Thus, an epithe lioma may develop from lupus; a keloid, especially in the colored race, from a scar; or a cancer at the border of a gastric ulcer. Cancer may also occur in the floor of a tuberculous or syphilitic gran ulating area, and an adenocarcinoma in the large intestine from a healing or healed typhoid ulceration.