Abstract
The case involved a 34-year-old man who was diagnosed with ulcerative colitis (UC) at the age of 16 and thereafter kept receiving treatment for UC. He visited our hospital because of left lower quadrant abdominal pain. Colonoscopy and abdominal computed tomography showed the wall thickening and stenosis in the sigmoid colon and abscess in the vicinity of it. As the first stage of the three-stage surgery, subtotal colectomy and ileostomy were performed. Postoperative histopathological examination revealed a number of noncaseating granulomas, so his diagnosis of UC changed to Crohn's disease (CD). We initially had planned to perform residual rectum extraction and ileal pouch anal anastomosis for the second stage surgery, but in addition to the diagnosis change, adenocarcinoma was detected at a polyp of the residual rectum, so that we performed abdominoperineal resection of the residual rectum. Histopathological examination showed carcinoma and dysplasia extensively not only at the polyp but also in the surroundings. In the patients with non-typical UC, there is a possibility that the diagnosis changes to CD. Also, the surgical procedures should be chosen attentively when colitic cancer is complicated, because carcinoma may be present more widely than it looks.
