Mistakes may occur as to the diagnosis between gastric cancer and tumors of the omenta, the mesentery, the transverse colon, the lymphatic glands, and even the spleen or the kidney. Encapsulated peritoneal exudations near the stomach have been mistaken for gastric cancer. Where a mistake is likely to occur each individual case presents its own peculiarities, which it is impossible to deal with in a general way. Of the utmost importance is a careful physical exploration of the characters and relations of the tumor, aided, if necessary, by artificial distension of the stomach or of the colon by gas (see page [549]). No less important is the attentive observance of the symptoms of each case. In doubtful cases fluids withdrawn from the stomach by the stomach-tube should be carefully examined for cancerous fragments, and the gastric fluids may be tested for free hydrochloric acid by methods already described.
Pyloric cancers which receive a marked pulsation from the aorta sometimes raise a suspicion of aneurism, but the differential diagnosis is not usually one of great difficulty. Gastric cancer when it presses upon the aorta may simulate aneurism, not only by the presence of pulsation, but also by the existence of a bruit over the tumor. The tumor produced by aneurism is generally smoother and rounder than that caused by cancer. The pulsation of an aneurism is expansile, but the impulse of a tumor resting upon an artery is lifting and generally without lateral expansion. The impulse transmitted to a tumor resting upon the abdominal aorta may be lessened by placing the patient upon his hands and knees. Sometimes the tumor can be moved with the hands off from the artery, so that the pulsation momentarily ceases. A severe boring pain in the back, shooting down into the loins and the lower extremities, and not dependent upon the condition of the stomach, characterizes abdominal aneurism, but is not to be expected in gastric cancer. With aneurism gastric disorders and constitutional disturbance are much less prominent than with cancer of the stomach.94
94 In a case of pulsating pyloric cancer observed by Bierner the symptoms were much more in favor of aneurism than of cancer. The cancer had extended to the retro-peritoneal glands, which partially surrounded and compressed the aorta. There were marked lateral pulsation of the tumor, distinct systolic bruit, diminution of the femoral pulse, and severe lancinating pain in the back and sacral region. With the exception of vomiting, the gastric symptoms were insignificant. The patient was only thirty-three years old (Ott, Zur Path. des Magencarcinoms, Zurich, 1867, p. 71).
Spasm of the upper part of the rectus abdominis muscle may simulate a tumor in the epigastric region. The diagnosis is made by noting the correspondence in shape and position between the tumor and a division of the rectus muscle, the superficial character of the tumor, the effect of different positions of the body upon the distinctness of the tumor, the tympanitic resonance over the tumor, and, should there still be any doubt, by anæsthetizing the patient, when the phantom tumor will disappear. Spasm of the rectus muscle has been observed in cases of cancer of the stomach.
Attention is also called to the possibility of mistaking in emaciated persons the head of the normal pancreas, or less frequently the mesentery and lymphatic glands, for a tumor.95 As emaciation progresses the at first doubtful tumor may even appear to increase in size and distinctness.
95 In the case of the late Comte de Chambord the diagnosis of gastric cancer was made upon what appeared to be very good grounds. No cancer, however, existed, and the ill-defined tumor which was felt during life in the epigastric region proved to be the mesentery containing considerable fat (Vulpian, "La dérnière Maladie de M. le Comte de Chambord." Gaz. hebd. de Méd. et de Chir., Sept. 14, 1883).
It is sufficient to call attention to the danger of mistaking, in cases where the gastric symptoms are not prominent and no tumor exists, gastric cancer for pernicious anæmia, senile marasmus, or the chronic phthisis of old age. In some of these cases the diagnosis is impossible, but the physician should bear in mind the possibility of gastric cancer in the class of cases here considered, and should search carefully for a tumor or other symptom which may aid in the diagnosis.
The possibility of mistaking gastric cancer accompanied with peritoneal exudation for cirrhosis of the liver or for tubercular peritonitis is also to be borne in mind.
The diagnosis of the position of the cancer in the stomach can usually be made in cases of cancer of the cardia or of the pylorus. The symptoms diagnostic of cancer of the cardia are dysphagia, regurgitation of food, obstruction in the passage of the oesophageal bougie, and sinking in of the epigastric region in consequence of atrophy of the stomach. It has already been said that catheterization of the oesophagus does not always afford the evidence of obstruction which one would expect. Cancerous stenosis of the cardia is to be distinguished from cicatricial stenosis in this situation. The diagnosis is based upon the history of the case, which is generally decisive, and upon finding fragments of cancer in the tube passed down the oesophagus.
That the cancer is seated at the pylorus is made evident by the situation of the tumor (see p. [561]) and by the existence of dilatation of the stomach. There are many more causes of stenosis of the pylorus than of stenosis of the cardia, so that, notwithstanding the absence of tumor, cancer of the cardia is often more readily diagnosticated than cancer of the pylorus.