These exist in about 35 per cent, of all cases of carcinoma of the stomach, and occur most frequently when the greater part of the organ or its upper margin is affected by the disease. Secondary growths are chiefly met with in the great omentum, which becomes converted into a hard, nodular, sausage-shaped mass adherent to the anterior aspect of the stomach or colon. Less frequently the general surface of the peritoneum presents numerous discrete tumours, which vary in size from a pea to a Tangerine orange, and are especially abundant in the pelvis and in the mesentery. Finally, in rare cases the serous membrane exhibits a diffuse miliary carcinosis, which closely resembles tubercle in appearance and frequently extends through the lymphatics of the diaphragm to the pleurae or the pericardium. It is therefore obvious that, while secondary carcinoma of the peritoneum may present certain features which are common to each variety, the physical signs of the disease vary according to the size, situation, and number of the metastases.
Pain is an inconstant feature of the complaint, and when present it is distinguished with difficulty from that which accompanies the primary growth. It is usually most conspicuous before the development of ascites, and is especially severe in cases of miliary carcinosis, where its onset may be so sudden as to simulate acute general peritonitis. Flatulence and constipation are always marked symptoms, and the distension that ensues after meals is a constant source of complaint. An invasion of the general peritoneum is always accompanied by a rapid failure of strength, and life is seldom prolonged for more than three months. The chief signs of the disease consist of ascites and the presence of one or more palpable tumours in the abdomen.
Ascites often develops quite suddenly, but it is rarely excessive, and is apt to vary in amount from time to time. A sudden increase of weight which is sometimes observed during the course of the gastric complaint is usually due to peritoneal effusion. As a rule the fluid is easily detected by palpation and percussion, but when extensive adhesions exist between the intestines and the abdominal parietes it is apt to become encysted, and may then be mistaken for a tumour. In cases of miliary carcinoma the mesentery becomes gradually contracted, with the result that the intestines are drawn backwards to the spine and are completely concealed by the serous exudation. Under these circumstances the anterior aspect of the abdomen is dull on percussion, while a large tympanitic area exists posteriorly over the back and loins.
The fluid removed by tapping is usually of a clear amber colour, and according to Runeberg contains a much larger percentage of albumin (4-6 per cent.) than that of dropsical effusions (1 1/2-2 1/2 per cent.). Microscopic examination of the sediment sometimes reveals clumps of cancer cells, or isolated cells which show atypical mitoses. Colloid changes in the cells may be detected. When the peritoneal growths are numerous and very soft the fluid is often haemorrhagic, while in cases where there is obstruction of the thoracic duct or lacteals a chylous exudation is sometimes observed (Weiss). Paracentesis may be followed by the development of a cancerous nodule at the site of the puncture. The peritoneal tumours may be limited to the vicinity of the stomach or disseminated throughout the abdomen. The former condition, which is by far the more common, was observed in 22 per cent, of our cases, and the morbid growths were usually found after death to occupy the great omentum or the gastro-splenic or gastro-hepatic omentum. In such cases one or more tumours are detected in the epigastrium, left hypochondrium, or umbilical region, which present a somewhat indefinite outline, a hard nodular surface, and a dull note on light percussion. At an early stage they move freely with respiration, but at a later period they are apt to become fixed by adhesions. Manipulation gives rise to pain, and periodic examinations reveal a progressive increase of size. In most instances the umbilicus becomes retracted, and fixed, and not infrequently a cordlike induration of the linea alba may be felt. Diffuse growths of the peritoneum were detected during life in only 2 per cent, of our cases of gastric carcinoma, and were always associated with ascites. They chiefly occur in the region of the umbilicus or near the caecum, where they give rise to hard, rounded, tender, and slightly movable tumours ; but sometimes the whole abdomen appears to be filled with masses of various sizes. It is in this condition that exploration of the pelvis is of such importance, since one or more growths may often be detected in the pouch of Douglas or between the bladder and the rectum long before a palpable tumour develops in the abdomen. Miliary carcinoma never gives rise to palpable tumours. Thrombosis of the femoral and saphenous veins, oedema of the legs, secondary nodules in the skin of the abdomen, and purpuric eruptions are liable to ensue during the course of the peritoneal disease.