Difficulty in differentiating two cases of sigmoid stenosis by diverticulitis from cancer

The incidence of colonic diverticulosis with or without diverticulitis has increased in the Japanese population due to the modernization of food and aging. The rate of diverticulitis in colon diverticulosis ranges from 8.1% to 9.6%. However, few cases of stenosis due to diverticulitis have been reported. These reports suggest that the differentiation between sigmoid diverticulitis and colon cancer is difficult. This report describes two cases of colon stenosis due to diverticulitis that were difficult to differentiate from colon cancer. Case 1 was a 70-year-old woman with narrowed stools for 1 month who underwent colonofiberscopy (CFS). CFS revealed a diverticulum and circumferential stenosis in the sigmoid colon. Barium enema revealed a marked, hourglass-shaped, 2-cm circumferential stenosis in the sigmoid colon. Fluorodeoxyglucose (FDG)-positron emission tomography computed tomography (CT) revealed an increased FDG uptake at the affected portion of the sigmoid colon. Sigmoid colon cancer was suspected, and laparoscopic sigmoidectomy was performed. Pathological examination demonstrated active inflammation with no evidence of malignancy. Case 2 was a 50-year-old man who presented to a nearby clinic with reduced stool output despite the urge to defecate. CFS detected severe stenosis in the sigmoid colon approximately 25 cm from the dentate line. Contrast-enhanced abdominal CT revealed multiple diverticula, wall thickening, and swelling of the lymph nodes around the peritoneal aorta and the inferior mesenteric artery. A partial sigmoidectomy was performed. Pathological examination of the resected specimen revealed no changes in the mucosal epithelial surface, but a marked infiltration of inflammatory cells was observed.