A Case of Intussusception Due to Sigmoid Colon Cancer

: A 78-year-old man was referred to our hospital with diarrhea, melena, and weight loss. During a digital rectal examination, a protuberant mass located 7-8 cm above the anal verge was palpable. Computed tomography(CT)scans of his chest, abdomen, and pelvis revealed an intestinal obstruction with a target sign in the lower rectum, indicating intussusception due to a sigmoid colon mass. A gastrografin enema examination revealed a typical filling defect with a crab claw sign in the rectum. However, the enema did not reduce the intussusception. The surgical findings showed that the sigmoid colon had slipped inside the rectum, consistent with the diagnostic imaging findings. A radical sigmoidectomy(D2)with diverting colostomy was performed to address the unprepared colon with accompanying edema. Pathology of the resected specimen revealed a type 2 tumor measuring 5 cm in size and comprising moderately differentiated adenocarcinoma(pT3pN0M0, pStage Ⅱ). The patient's postoperative course was uneventful, and his stoma was closed 2 months later. Intussusception occurs less frequently in adults than in children. In a case of bowel-within-bowel configuration, in which layers of the bowel are duplicated to form concentric rings, the target-like sign on CT images may be a useful diagnostic marker of colorectal intussusception.