Case 2 -

Diverticular Disease Associated Segmental Colitis Laura W. Lamps, M.D. Audrey J. Lazenby, M.D. Joel K. Greenson, M.D.

Clinical Presentation: These biopsies are from the sigmoid colon of a 67 year old man with abdominal pain and occasional diarrhea. Case 2 - Figure 1 - Note expansion of the lamina propria by a lymphoplasmacytic infiltrate, and moderate architectural distortion, resembling ulcerative colitis. Case 2 - Figure 2 - Note expansion of the lamina propria by a lymphoplasmacytic infiltrate, and moderate architectural distortion, resembling ulcerative colitis. Case 2 - Figure 3 - Cryptitis and prominent lymphoid aggregates may be present. Endoscopic Findings: The endoscopist noted mild erythema in the sigmoid colon that seemed to spare the rectum. Scattered diverticula were also noted. Diagnosis : Diverticular disease-associated segmental colitis General Comments: Diverticular disease is common among patients over the age of 60, particularly in the sigmoid colon. Recently, several reports of diverticular disease associated colitis have been published that describe a chronic segmental colitis that is present in the distribution of the diverticula, mimicking ulcerative colitis. This colitis is restricted to the mucosa and is not related to diverticulitis. Patients typically present with hematochezia. Another form of diverticular disease associated colitis mimics Crohn's disease. This form of colitis occurs in patients with diverticulitis who do not have evidence of Crohn's disease elsewhere in the gastrointestinal tract. The resection specimens demonstrate a Crohn's-like reaction to the diverticulitis. Pathologic features: Colonoscopic evaluation generally reveals patchy or confluent hyperemia, often accentuated on the crests of mucosal folds. The mucosa may appear granular, and an exudate is variably present. The distribution is predominantly descending colon and sigmoid, in the region of diverticular disease; the rectum is often spared. In the ulcerative colitis-like variant, histologically one will find a range of chronic changes in the lamina propria, from a mild plasmacytosis and mild crypt distortion to a full-blown ulcerative colitis-like appearance. Cryptitis and crypt abscesses are also seen. If the pathologist is not informed of the presence of diverticula he or she will have a hard time classifying this form of inflammatory bowel disease. The key to making the correct diagnosis rests with recognizing that the colitis is present only in the distribution of the diverticula. In the Crohn's like variant, there is segmental thickening of the bowel wall with fat wrapping, a cobblestone pattern of the mucosa and bear-claw-like ulcers. Serosal exudates and transmural sinuses are usually seen. Microscopically, nearly all the histologic features of Crohn's disease may be seen, complete with non-necrotizing granulomas. Of note, in one study, there was an absence of neural hyperplasia, gastric antral-gland type metaplasia and villiform mucosal surface changes. Pathologists must recognize this reaction pattern and not rush to make the diagnosis of Crohn's disease in a patient with no other history or risk factors for the disease. Pathogenesis and Natural History: The pathogenesis of this condition is uncertain. The ulcerative colitis-like variant resembles mild ulcerative colitis in both clinical course and histologic features. Some patients have, however, developed classic ulcerative colitis. Follow-up studies on the Crohn's-like variant have found that the vast majority of patients do not go on to develop Crohn's disease (much like isolated granulomatous appendicitis cases). Differential diagnosis: It can be very challenging to differentiate diverticular disease-associated colitis from Crohn's, ulcerative proctitis, or ulcerative colitis with rectal sparing. Patients with ulcerative colitis and rectal sparing tend to be younger and lack diverticula. In addition, even in ulcerative colitis with rectal sparing, the rectal mucosa is usually not absolutely normal (shows some features of quiescent colitis). Patients with Crohn's and ulcerative colitis tend to have involvement of other segments of the bowel. Treatment: The treatment of diverticular disease associated colitis varies from therapies aimed at diverticulitis (fiber and antibiotics) to anti-inflammatory therapies similar to those used for ulcerative colitis. Some patients are refractory to medical management and require surgical resection. References: Peppercorn MA. Drug-responsive chronic segmental colitis associated with diverticula: a clinical syndrome in the elderly. Am J Gastroenterol. 87:629-32;1992. Makapugay LM, Dean PJ: Diverticular disease-associated chronic colitis. Am J Surg Pathol 20:94-102,1996. Sladen GE, Filipe MI. Is segmental colitis a complication of diverticular disease? Dis Colon Rectum 27:513-4;1984. Hart J, Baert F, Hanauer S. Sigmoiditis: a clinical syndrome with a spectrum of pathologic features, including a distinctive form of IBD (abstract). Mod Pathol 8:62A;1995. Goldstein NS, Leon -Armin C, Mani A: Crohn's colitis-like changes in sigmoid diverticulitis specimens is usually an idiosyncratic inflammatory response to the diverticulosis rather than Crohn's colitis. Am J Surg Pathol 24:668-675;2000. Gledhill A, Dixon MF. Crohn's-like reaction in diverticular disease. Gut 42:349-353;1998. Burroughs SH, Bowery DJ, Morris-Stiff GJ, Williams GT: Granulomatous inflammation in sigmoid diverticulitis: two diseases or one? Histopathology 33:349-353;1998.