A well localized inflammatory process involving only the sigmoid colonic segment associated with diverticulosis (SCAD), has become increasingly recognized as a distinct clinical and pathological disorder, usually described in older adults, often with rectal bleeding. Although some resolve spontaneously, most patients appear to respond to treatment only with 5-aminosalicylate. Endoscopic evaluation reveals a nonspecific inflammatory process localized in the sigmoid colon that usually completely resolves with histologically normal colonic mucosa. Recurrent symptoms with evidence of recurrent segmental colitis may occur, but most have an entirely benign clinical course. Further definition of the underlying molecular signalling that occurs in this apparently distinctive disorder may be critically important to understand the elements of a colonic inflammatory process that can completely and spontaneously resolve.