Excavated mass and doubletracking in the sigmoid colon due to colocolic fistula complicating diverticulitis.

We report on a patient admitted for work up of prostatic carcinoma in which CT study showed an excavated mass involving the sigmoid colon and the bladder dome. Barium enema showed a double track pattern associated with diverticular disease. By surgery the mass was separated from the urinary bladder and the sigmoid resected. On pathological exam diverticulitis was evident as well as an organised colocolic fistula in the thickened fibrotic subserosal fat.The usefulness of opacifying the colon is highlighted.