A 65-year-old man with intermittent, colicky periumbilical pain which first occurred two months earlier was admitted to hospital. He had an eight-year history of congestive heart failure caused by mitral valvular regurgitation and atrial fibrillation. He was nonalcoholic, and there was no history of diarrhea, hematochezia, or melena. Physical examination showed an increased bowel sound. Vital signs at admission were stable, and laboratory findings including white blood cell count, a liver function test and electrolytic balance were within the normal ranges. Electrocardiography revealed atrial fibrillation, and chest radiography demonstrated cardiomegaly (not shown). To exclude acute appendicitis, initial ultrasonography (US) was performed, and this demonstrated diffuse, segmental, concentric wall thickening of the terminal ileum just proximal to the ileocecal valve. The mucosal folds were blunted and there was low level echogenicity (Fig. 1A). Nonspecific ileitis, Crohn's disease, intestinal tuberculosis or ischemic enteritis were suggested as possible causes of the bowel wall thickening, and in order to evaluate the terminal ileum, colonoscopic examination was performed. The ascending colon was found to be completely obstructed by a circumferential mass lesion, and the colonoscopic fiber could not be advanced further. Subsequent CT scanning showed a markedly dilated small bowel and ascending colon, with concentric, hyperattenuating, focal wall thickening in the hepatic flexure of the ascending colon (Fig. 1B). In addition, the terminal ileum was dilated and showed diffuse, concentric wall thickening of its long segments with heterogeneous contrast enhancement. In the thickened wall, focal areas of poor contrast enhancement were also noted (Fig. 1C). There appeared to be several possible diagnoses, including ischemic enterocolitis caused by thromboembolism of mesenteric vessels arising from atrial fibrillation, inflammatory bowel disease involving the ascending colon and terminal ileum, and ischemic or infectious enteritis associated with colon cancer. Although surgery was recommended, the patient refused. Stool culture yielded lactose-fermenting Gram-negative bacillus, urine culture yielded Citrobacter freundii, and Gram staining of urine revealed the presence of Gram-negative rods; no organisms were isolated from blood cultures. In addition to conservative management of congestive heart failure, the patient underwent antibiotic therapy with amoxacillin, tobramycin or aztreonam for two weeks and ciprofloxacin for several days. Symptoms such as abdominal pain ameliorated, the level of bowel sound decreased, and laboratory findings continued to be within normal ranges. Vital signs were stable, except for intermittent fever of up to 38.2C until 30 days after admission. At this time, the patient complained of sudden abdominal pain and his clinical condition deteriorated. Emergency right hemicolectomy was performed, with resection of the distal ileum. At surgery, the hepatic flexure of the ascending colon was found to be completely obstructed by a hard concentric mass, and about 15 cm of the terminal ileum, just proximal to the ileocecal valve, was markedly dilated and diffusely thickened. About 500 ml of clear, yellowish ascites was also present. A cut section of the thickened terminal ileum revealed marked submucosal edema to a depth of approximately 10 mm, though there was no evidence of mucosal lesion. The colonic mass was confirmed microscopically as a poorly differentiated adenocarcinoma. Microscopic examination also showed that the mucosal folds of thickened ileal loop were blunted by submucosal edema and there was extensive inflammatory reaction, with infiltrations of neutrophils. In some areas of the thickened bowel wall, there was extensive destruction of underlying tissue by irregular-shaped abscesses. Neutrophil infiltration extended into the subjacent muscular layer and even to the serosa (Fig. 1D). The inflammatory reactions provided no evidence of granuloma formation, and the histologic findings were consistent with phlegmonous enteritis.