Appendiceal orifice inflammation as a skip lesion in ulcerative colitis: Relation to medical therapy and disease extent

Several studies using colectomy specimens and a recent endoscopic study (Am J Gastroenterol 1997;92:1275) have claimed that the appendix can be involved as a skip lesion of ulcerative colitis (UC). However, as these studies were performed in patients with preexisting UC, they could not exclude the possibility of the skip lesion developed as a result of medical therapy. A prospective study was performed to determine the frequency of appendiceal orifice inflammation (AOI) as a skip lesion of UC in both the prevalent and incident cases, and to evaluate the relationship between the presence of AOI and the extent of disease. Methods: Of 149 UC patients who underwent colonoscopy between Mar. 1996 and Oct. 1997, 86 patients (prevalent 61; incident 25) were included in this study. Sixty-three patients were excluded because of 1) the failure of colonoscopy to reach the cecum (n=18), 2) the past or present involvement of the ascending colon (n=31) and 3) no active disease at the time of colonoscopy (n=14). Photographs and biopsy tissues were taken from each segment including appendiceal orifice, cecum and ascending colon. Positive AOI was defined as the presence of the definite macroscopic lesion supported by microscopic findings of more severe inflammation at the appendiceal orifice compared with the cecum or the ascending colon. Results: AOI was noted in 22 (26%) of 86 patients with active non-universal UC. No difference in the frequency of AOI was noted between the prevalent patients (23%) and the incident patients (32%). In the combined group of prevalent and incident patients, the frequency of AOI decreased significantly as the extent of disease increased: 35% in patients with proctitis (n=46), 19% in left-sided colitis (n=32), and 0% in extensive colitis (n=8) (p<0.05). Conclusions: AOI as a skip lesion of UC is 1) not rare, 2) more frequent in patients with narrower extent of disease and 3) not the result of patchy improvement from the medical therapy.