Clinical and colonoscopic investigation of skipped periappendiceal lesions in ulcerative colitis

Background: Ulcerative colitis (UC) is typically a continuous and diffuse inflammation extending proximally from the rectum. However, skipped lesion in the appendiceal region has been reported recently. Although appendectomy has been shown to reduce the risk of UC, the clinical significance of skipped periappendiceal lesion remains unclear. The present study examined the relationship between the continuous distal lesion of UC and the skipped periappendiceal lesion by observing colonoscopic changes in both lesions. Methods: Among 279 patients with UC who underwent total colonoscopy from January 1994 to December 2000, 54 patients ( 19.4%) had skipped periappendiceal lesions. Serial colonoscopic examinations were performed in 35 of the 54 patients to determine the activities in the distal UC lesion and skipped periappendiceal lesion during the course of disease. Results: Patients with skipped periappendiceal lesions were younger and had a longer history of UC than those without them, but no differences in sex ratio and treatment modality were observed between the two groups. In 28 of 35 patients (80%), the activity in the distal lesion correlated well with that in the skipped periappendiceal lesion. Both lesions were improved in 17 patients, unchanged in 5 patients and worsened in 6 patients. Linear regression analysis showed a significant correlation between the changes in colonoscopic activity index in the two lesions. Conclusion: A close association is found between disease activity in the skipped periappendiceal lesion and that in the distal lesion of UC.