Metastatic Lesions to the Large Intestine

A review of surgical specimens or operative notes and autopsy material will indicate that metastatic lesions affecting the colon are not uncommon. When the roentgenological features of numbers of such cases are studied, special patterns evolve which may be quite impressive. Familiarity with the changes that are produced by cancer metastases, either in direct contact with the wall of the large intestine or implanted in the mesentery, permits the roentgenologist to offer this opinion as one of highest probability among several that may be considered. The routes by which metastases reach the colon include: the embolic, either lymphatic or vascular; direct extension, with invasion of the contiguous colon wall; seeding or implantation of malignant cells. This last may occur because of free cells in the peritoneal fluid or because of manipulation of the primary lesion at the time of surgery. It is felt that metastatic implants in the mesentery may produce some functional changes even if the intestinal wall is not directly involved. The method by which the colon becomes affected is of some significance in explaining the type of lesion produced. Those derived by direct extension will simulate primary carcinoma more closely. In fact, lesions of this type can produce complete retrograde obstruction. In these cases, however, there may exist the knowledge that an adjacent viscus is the site of a primary cancer. Abnormalities produced by seeding or embolization are more likely to be multiple, and eccentric in character; they also may exhibit changes of a pathophysiological nature that are best appreciated by roentgenoscopy. In the 30 cases reviewed, the ages ranged from thirty-two to eighty-five years. There were 7 males and 23 females. All of the lesions were intra-abdominal or pelvic in origin, except for 2 cases secondary to breast carcinoma and one to squamous-cell carcinoma of the leg. Two patients had had a primary malignant neoplasm of the large intestine but the history and the surgical and pathologic findings indicated that the newly discovered lesions were not additional primary carcinomas but were truly metastatic in type. Most of the patients were admitted with gastrointestinal symptoms, many of them giving a history of constipation and change in bowel habits. Several had a preceding history of a primary cancer elsewhere. In most of the cases of diffuse carcinomatosis resulting from gastric, pancreatic, and ovarian tumors, the origin of the cancer was not known before surgery or postmortem study. In such patients, when barium-enema examinations were done, it was not usually known that a primary cancer existed outside of the colon. It is of particular interest, therefore, that the roentgenologist did not offer a diagnosis of primary cancer, but more usually of inflammatory disease or, in the more recent cases, of metastasis.