DEFINITION.—Under the term carcinoma of the liver are included primary and secondary cancer of the liver. The malady with which we are now concerned is the primary affection, occurring in the organ proper or in some pathological new formation connected with it.
ETIOLOGY.—Heredity is the most important factor. A careful investigation of the reported examples demonstrates that from 15 to 20 per cent. owe their origin to hereditary influence clearly, and probably considerably more are indirectly derived in this way when the immediate connection may not be demonstrable. Next to heredity, age must be regarded as the most important pathogenetic influence, much the largest number occurring at from forty to sixty years of age. It is a malady of advanced life, therefore, rather than of youth or middle age. Excluding the female organs from consideration, it is quite certain that sex has little special influence, and that males and females are affected about equally.
Primary cancer of the liver is comparatively infrequent, occurring in not more than one-fourth of the cases. Frerichs collected 91 cases, and of these 46 were secondary to cancer in organs having vascular communication with the liver.
PATHOLOGICAL ANATOMY.—Under the term cancer of the liver are included several distinct forms of morbid growth, but united in the characteristic of malignancy. From the merely clinical standpoint this characteristic is the most decisive bond of union between them, and serves as the point of departure in the study of this affection. Primary cancer of the liver is divisible into two forms: 1, as a single, defined tumor; 2, as an infiltration through the whole mass of the organ.140 Secondary cancer occurs in nodular masses, and with extreme rarity as an infiltration. The form of cancer is really the same; the differences in structure are only apparent, the variations being due to the relative proportion of cells, fibres, and vessels. If the fibrous stroma is abundant and the cells small in quantity, the form of structure approaches scirrhus; on the other hand, if the cells largely preponderate, the type is encephaloid; if vessels predominate, it is called telangiectatic. The usual form in cancer of the liver is the soft, cellular variety, encephaloid or medullary. When the cancerous new formation is nodular, the masses vary in size from a pea to a child's head,141 and are numerous inversely as their size. When the cancer occurs as a solitary tumor, it may attain to enormous dimensions. It has a spherical shape usually, protrudes from the surface of the organ somewhat irregularly, and the overlying peritoneum is thickened, cloudy, and adherent from a local inflammation. The central portion, whether there be one, several, or many nodules, is depressed, giving an umbilicated appearance to the tumor; and this central depression is found to be soft, almost diffluent, and full of juice. The fibrous stroma which extends through this central soft material has a reticulated arrangement and a shining, fibrous appearance. The cancerous masses are not confined to these nodules, but extend into the surrounding hepatic structure, push their way into the portal (especially the hepatic) veins, block the ducts, and invade the lymphatic glands in the fissure of the liver.
140 Virchow, Krankhaften Geschwülste, loc. cit.; Perls, Virchow's Archiv für path. Anat., etc., Band lvi. p. 448 et seq.; Frerichs, A Clinical Treatise, etc., Syd. Soc. ed., loc. cit., vol. ii. p. 281 et seq.
141 Förster, Lehrbuch der Pathologischen Anatomie, by Seibert, Jena, 1873.
When the cancerous new formation takes the form of an infiltration of the organ instead of distinct nodules, the liver is usually uniformly enlarged and its outlines preserved.142 The peritoneum is opaque, thickened, and adherent. The organ is traversed by fibrous bands, and the intervening portion is a soft, juicy pulp, stained by the imbibition of bile. In extreme cases hardly any portion of the proper hepatic tissue remains, but is replaced by a cancerous new formation having the same shape.
142 Perls, Virchow's Archiv, Band lvi. p. 448 et seq.
As regards the minute structure of cancer of the liver, it may be regarded as a degeneration (cancerous) of the proper gland-cells and of the epithelium of the bile-ducts. As cancer develops in the liver it is to be noted that the cellular elements preponderate over the fibrous or the stroma, and hence the new formation presents the characteristics of softness, rapid growth, and a multitudinous cellular hyperplasia. As regards the form of the new cells, it cannot now be doubted that they are descendants of the secretory gland-cells and of the epithelial lining of the ducts. According to some observers, it is to the proliferation of the proper gland-cells that the new formations owe their origin; according to others, to the hyperplasia of the cells lining the ducts. As the growth of the new formation can take place only through an adequate blood-supply, it becomes very important to ascertain its source. There can be little doubt that primary cancer of the liver receives its nutrient supply through the hepatic artery, in connection with which new capillaries form in the pathological tissue.
Secondary cancer of the liver is the usual form of the specific manifestation. From the merely clinical standpoint the primary affection is the more important. From the pathological point of view the secondary implication of the liver may be a true metastasis or a mere communication by contiguity of tissue. The most usual metastasis occurs from epithelial cancer of the face (Schüppel), but the ordinary communication of the new formation is from primary cancer of the stomach, intestine, pancreas, mesentery, etc. The cancer elements, as the author has several times verified, crowd the lymphatics and veins, and through these channels reach the liver and other parts. As the cancer elements in the case of secondary implication of the liver are distributed chiefly by the portal vein, it follows that there must be numerous secondary foci and multiple nodes. Cancerous infiltration under these circumstances is the rarest possible form for the new growth to take. The size and number of nodes forming in these cases of secondary implication of the organ vary greatly—from two or three to twenty, or a hundred, or even more. As regards the form, structure, and ultimate behavior of the secondary formation, they do not differ from the primary. As respects the relative proportion of stroma and cellular elements—fibres and cells—they vary greatly, some presenting the firm texture of a predominating fibrous stroma, others the softness and ready diffluence of the excessive cellular production. The latter is undoubtedly the usual condition, and when the nodular masses are incised an abundant creamy juice exudes. With the development of these nodules an increase in the size of the liver takes place and the organ has an uneven and indurated feel. As the cancerous masses develop the proper hepatic structure undergoes atrophy, and finally little is left of the organ but the cancerous new formation. The blood-vessels, lymphatics, and peritoneal investment are invaded, the first mentioned most decidedly; and especially are organized exudations the favorite seats of cancer new formations, those, for example, about the gall-bladder and cystic duct resulting from repeated attacks of passage of calculi.