[Extracolonic-infiltrative process of the sigmoid colon and the rectosigmoid junction]

The problems of extracolic-infiltrative lesions of the sigmoid colon and recto-sigmoid junction are discussed, based on representative case studies. Because of the localisation of these bowel segments in the lower peritoneal cavity, they can be reached by direct infiltration of contiguous tumors--especially carcinoma of the ovary--or by seeding into the pouch of Douglas and the sigmoid mesocolon. In many cases characteristic roentgen-morphologic features indicate a secondary infiltration, but inflammatory and malignant lesions have to be differentiated. The differential-diagnosis must consider also diverticulitis, endometriosis and extracolic growth of colonic carcinoma. Additional ultrasonography and computed tomography may help to clear topographical relations and to detect direct and indirect signs of peritoneal carcinomatosis and abscess.