Scirrhous cancer assumes often the form of a diffuse thickening and induration of the gastric walls, particularly in the pyloric region, where it causes stenosis of the pyloric orifice. Scirrhus may, however, appear as a circumscribed tumor. Irregular hard nodules frequently project from diffuse scirrhous growths into the interior of the stomach. Scirrhous cancer and medullary cancer are often combined with each other.
The dense consistence of scirrhous cancer is due to the predominance of the fibrous stroma, the cancerous alveoli being relatively small in size and few in number.
Colloid cancer generally appears as a more or less uniform thickening of the gastric walls. All of the coats of the stomach are converted into the colloid growth. Nearly the whole of the stomach may be invaded by the new growth.82 The tumor has a tendency to spread to the omenta and to the rest of the peritoneum, where it may form enormous masses, but it rarely gives rise to metastases in the interior of organs. Colloid cancer may, however, form a circumscribed projecting tumor in the stomach, and in rare instances it causes abundant secondary colloid deposits in the liver, the lungs, and other parts.
82 In a case reported by Storer the whole stomach, except a little of the left extremity over an extent of about an inch, was converted into a colloid mass in which no trace of the normal coats of the stomach could be made out. The colloid growth replacing the gastric wall measured seven-eighths of an inch in thickness in the pyloric region. Digestion was less disturbed in this case than in most cases of gastric cancer (Boston Med. and Surg. Journ., Oct. 10, 1872). In Amidon's case (reported in the Trans. of the N.Y. Path. Soc., vol. iii. p. 38) there seems to have been an equally extensive colloid metamorphosis of the stomach.
Colloid cancer presents, even to the naked eye, an exquisite alveolar structure, whence the name alveolar cancer as a designation of this tumor. Bands of opaque white or gray connective tissue enclose alveolar meshes which are filled with the gelatinous, pellucid colloid substance. This colloid material is thought to be produced by a colloid transformation of the epithelial cells in the alveoli, but the same transformation seems to occur also in the stroma. Few or no intact epithelial cells may be found in the alveoli. Colloid metamorphosis may take place in all forms of gastric cancer, but it is particularly common in cylindrical epithelioma. Colloid cancer may originate in the peritoneum unconnected with any glandular structures. It occurs often at an earlier age than other forms of cancer. Deep ulceration rarely attacks colloid cancer.
Flat-celled epithelioma is found at the cardiac orifice and as a metastatic growth in other parts of the stomach. Originating in the oesophagus, it may extend downward into the stomach. By noting whether the structure is that of squamous or of cylindrical epithelioma it is often possible to determine whether a tumor at the cardiac orifice originates in the oesophagus or in the stomach.
Secondary cancer of the stomach, although rare, is not such a curiosity as is often represented. Without aiming at completeness, I have been able to collect 37 cases of secondary cancer of the stomach, of which the larger number will stand critical examination.83 Of these cases, 17 were secondary to cancer of the breast, 8 to cancer of the oesophagus, 3 to cancer of the mouth or nose, and the remainder to cancer of other parts of the body. The large number of cases secondary to cancer of the breast is explained by the large statistics relating to mammary cancer which were consulted. Gastric cancer is more frequently secondary to cancer of the oesophagus than to cancer of any other part. In this category of course are not included cases of continuous growth of oesophageal cancer into the stomach, but only metastatic cancers of the stomach. A part at least of the gastric cancers secondary to cancer of the alimentary tract above the stomach I refer, with Klebs, to implantation in the mucous membrane of the stomach of cancerous particles detached from the primary growth in the oesophagus, pharynx, or mouth. This view is supported by the absence in some cases of any involvement of the lymphatic glands. The secondary deposits in the stomach conform in structure to the primary growth. They are usually situated in the submucous coat, where they form one or often several distinctly circumscribed tumors. The secondary tumors may or may not ulcerate. They rarely produce symptoms.
83 These cases are from Dittrich, 2 (the remainder of his cases I rejected); Cohnheim, 1; Petri, 2; Klebs, 3; Lücke, 1; Weigert, 1; Coupland, 1; Cruse, 1; Hausmann, 1; Bartholow, 1; Oldekop, 5; Edes, 1; V. Török and V. Wittelshöfer, 8; Grawitz, 4; Haren Noman, 5. So-called melanotic cancers, cancers involving only the serous coat of the stomach, and those extending by continuous growth into the stomach, are not included in this list.
Primary cancers may be present at the same time in different organs of the body; for instance, in the uterus and in the stomach.84 The possibility of multiple primary cancers is to be borne in mind in considering some of the apparently secondary cancers of the stomach, as well as in determining whether certain cancers are secondary to gastric cancer or not. Here the microscopical examination is often decisive.85
84 Case of A. Clark's (Trans. N.Y. Path. Soc., vol. i. p. 260), and a similar one reported by J. B. S. Jackson in Extr. from Records of the Boston Soc. for Med. Improvement, vol. i. p. 335.