Page:The New International Encyclopædia 1st ed. v. 19.djvu/612

* TUMOR. 532 TUMOR. sues of epiblastie origin. It originates in any of the various forms of epithelium. It is not be- lieved to occur as a primary tumor in such tis- sues as bone, muscle, etc., which originate in other embryonic layers. Carcinoma may, however, involve any of the body tissues. When it involves tis.sues other than epithelial, it is probable that the growth is secondary, the pri- mar_v tumor in epithelium being so small as to have passed unrecognized. The very hard and firm form of carcinoma so common in the female breast is known as 'scirrlious cancer' or fibro-carcinoma. Its hardness is due to the large amount of dense fibrous tissue, the cellular elements being comparatively few. Very soft ear- cinoniata, made up almost entirely of cells with a minimum amount of connective tissue, are called 'medullary cancer' or carcinoma moUe. Melano-earcinomata are tumors in which more or less brown or black pigment is deposited in the cells or in the connective-tissue stroma. Carcinoniata whose cells have undergone mucoid degeneration or whose stroma is of the type found in mucous connective tissue are known as 'carcinoma my.vomatodes.' Gelatinoxis carcino- ma is a form of carcinoma in which the cells be- come filled with a translucent gelatinous mate- rial. In some tumors these di'oplets of gelati- nous substance, which have taken the place of the epithelial cells, coalesce to form considerable areas of gelatinous material. These areas fre- quently give an alveolar appearance, for which reason this form of carcinoma is frequently re- ferred to as 'alveolar carcinoma.' Epithelioma is a form of carcinoma which ■originates in squamous epithelium. Tlie struc- ture of the tumor tissue corresponds roughly to that of squamous epithelium as seen in the skin and mucous memlirancs. Thus there are flat- tened squamous surface cells, irregular cells such as are found in the deeper layers of the skin, 'prickle' cells, cidjoidal cells, etc. Not in- frequently squamous cells are packed in to- gether in crescentic forms known as epithelial 'pearls.' Epithelioma or 'epithelial cancer' is most common around the orifices of the body where skin and mucous membranes unite, as for example around the openings of the mouth, nose, eyes, vagina, etc. The malignancy of an epithe- lioma depends much upon the growth powers of its cells and the extent to which these cells tend to infiltrate surrounding tissues. In general it n.ay be said that epitheliomata are the most slow growing and least malignant of all forms of cancer. They may, however, recur unless completely removed and may form metastases. Malignancy of Tumors. Many tumors which are in themselves benign in character may be dangerous to life from their positiim and conse- quent interference with the functions of impor- tant organs. Such tumors, although sometimes causing death, are not classed as malignant tumors. Malignant tumors proper present cer- tain well-defined characteristics of their malig- nancy. Among these may be mentioned, first, their tendency to local recurrence after removal. This has led to the rule of the surgeon when operating on cancer to cut wide of the growth, even though the tumor may seem small and in- significant, in the hope of removing all trace of cancerous tissue even at the sacrifice of some healthy tissue. This local recurrence after ap- parently complete removal is undoubtedly due to tile fact that cancer cells have e.vtcnded out beyond the limits of the visible tumor. It is cusl(jmary in some cases to have immediate mi- croscopical examination made of the periphery of the mass removed, to determine the presence or absence of cancer cells at the outer limits of the operation. Secondly may be mentioned the tendency of a malignant tumor to extend by direct conti- nuity of growth to surrounding tissues. In 'dis- contiiuious peripheral growth' there are at first microscopic extensions outward of cancer cells from the periphery of the tumor. These grow and form nodules near, though at first separated from, the main tumor mass, but which after- wards spread and usually join the original tumor. A third and very ch.aracteristic mark of malignancy in a tumor is the formation of what are known as metastatic tumors. These are sec- ondary tumors of the same general nature as the parent growth. They may occur in any tis- sue or organ, no matter how distant, and are the result of cancer cells disseminated through the blood and lymph. These cells, lodging, form the starting points of new or secondary or meta- static growths. These secondary growths may also act as new centres of infection from which other metastatic tumors may arise. A fourth evidence of malignancy is the effect of the pres- ence of the cancer upon the general health of the patient. General impairment of the patient's health is due to many factors, such as the drain upon the whole system of a rapid new growth, the absorption of injurious matter from the tumor itself, the eflfect of suppuration or necro- sis, etc., and is known as 'cancerous cachexia.' Development and TEEAxitENT of Certain TriioR.s. Carcinoma, or scirrhous cancer, is the form most frequently seen in the breast, where it is invariably primary. It follows a blow or other injury, in many cases; often no cause can be assigned. It most commonly commences as a small, circumscribed tumor, round, hard, slowly growing, and with little or no pain. As it in- creases in size it becomes irregular, granular, and adherent to the adjacent parts. Infiltration of the surrounding structures follows, the pectoral muscles may become involved, and the skin may become attached. The skin also becomes stretched and shining. stiflF and brawny. CEdema of the arm follows, with enlargement of the axillary glands. The pain now becomes intense and fair- ly constant, extending not only to the shoulder, but down the arm to the hand. The nipple, as in some non-malignant tumors, becomes retracted and deeply attached. As the process goes on the cellular tissue, intercostal muscles, and ribs may become attacked, the pleura may be in- vaded, and hydrothorax as well as visceral de- posits mav follow. The duration of life after the occurrence of scirrhus of the breast is about three years. In old people the progress is slow, and in a few recorded cases life was prolonged for ten years. Most cases occur between the ages of thirty and forty-five years. The treatment consists of removal of the growth as early as found. In most cases the whole breast should be removed, and the axilla be laid open, that all enlarged