Purpose: This study is designed to describe colonic histology in patients with primary sclerosing cholangitis (PSC) without clinical symptoms of inflammatory bowel disease (IBD) and to do a follow-up study of these patients to find the time span from first detection of histologic signs until development of clinical symptoms of IBD.
Methods: In a cohort of 76 patients with PSC treated at Huddinge University Hospital, 11 patients did not have any clinical symptoms of IBD at the time of PSC diagnosis. Nine of these patients underwent diagnostic colonoscopy with multiple biopsies.
Results: In the group of nine PSC patients, without clinical signs of IBD undergoing colonoscopy, histologic signs of IBD were found in seven patients (6 ulcerative colitis and 1 Crohn's disease). Among them one had dysplasia, and another had epithelial changes probably positive for dysplasia. Two other patients had histologic signs of inflammation, however, not fully compatible with IBD. Three of 11 patients developed clinical symptoms of IBD after one, three, and seven years of follow-up since diagnostic colonoscopy.
Conclusions: In patients with PSC, histologic signs of IBD, including premalignant changes, may precede development of clinical symptoms of IBD by as much as seven years. This indicates that IBD onset may have a substantial subclinical phase of IBD far longer than previously appreciated. This finding may be of clinical importance because underestimation of disease duration may delay inclusion of PSC patients with extensive colitis in colonoscopic surveillance programs. The subclinical phase may also allow the studies of early pathogenesis in vivo.