An gland shows an area of rupture with acute inflammatory material.

The deeper portions of the bowel wall show nodular lymphoid aggregates in a Crohn's-like fashion. Fissures and ulcers in areas away from the diverticula are suggestive of co-exiting Crohn's.

The muscular wall is markedly thickened and there is neural hyperplasia.

Abscess collections are found in the wall.

The most common site for diverticula is the left side of the colon, especially the sigmoid colon. Colonic diverticula becomes more common with aging. Weakness of the colonic wall from intraluminal pressure is thought lead to the development of diverticula. The prevalence in Western countries rises to 50% by age 60 (Kumar). The incidence in Japan and Asia is lower. A fiber-deficient diet is thought to be a risk factor although a clear causal relationship has not been proven.

Grossly, diverticula appear as outpouching of the colon and may contain impacted fecal material. Since the colitis centers around diverticula, its segmental pattern may mimic ulcerative colitis. Histologically, the findings will differ depending on the extent of disease. Features include a chronic infiltrate in the lamina propria, distorted glands, crypt abscesses, cryptitis and crypt abscesses (Iacobuzio). In some instances, lymphoid aggregates, crypt abscesses and cryptitis may resemble Crohn's disease.

Patients with diverticulitis are usually older than 60. Most diverticula are incidental findings, although in 20% of cases, patients may experience cramping, constipation and hematochezia. Obstruction or perforation of the divericula may result in inflammation, fibrotic thickening of the bowel wall, pericolic abscesses and peritonitis. In rare instances, there may be massive hemorrhage (Kumar).

Fiber, antibiotics and anti-inflammatory agents are employed. In refractory or extensive disease, resection may be necessary.