Background: The pathologic features of ulcerative colitis (UC) in patients with primary sclerosing cholangitis (PSC) are, essentially, unknown. One previous clinical study suggested that UC-PSC patients reveal a high rate of rectal sparing and backwash ileitis. The purpose of this study was to systematically evaluate the pathologic characteristics and distribution of colonic disease in UC-PSC patients and to compare the results with a matched control group of UC patients without PSC.

Methods: Forty UC-PSC patients and 40 matched UC patients without PSC (controls) were identified from the files of 3 hospitals between the years 1989 and 2005. Clinical, endoscopic, and follow-up data (including incidence of pouchitis) were evaluated, and a detailed pathologic evaluation of biopsy and resection specimens (when available) was performed in a blinded fashion. The degree of activity and chronicity in mucosal biopsies and/or tissue from resection specimens was graded on a 5-point grading system (0 to 4), and each portion of the colon (cecum, ascending colon, transverse colon, descending colon, rectum) was assessed separately. Rectal sparing and patchiness of disease were evaluated, and scored as either absolute or relative depending on the complete absence of inflammatory disease in the former, or less inflammatory disease in the rectum compared with other parts of the colon in the latter.

Results: In this matched case-control study, UC-PSC patients presented at a significantly earlier age (24.5 y), had a higher prevalence rate of pancolitis (85%), and an overall significantly lower grade of inflammation in the colon (mean grade: 2.09+/-0.085) compared with UC controls (mean age: 33.8 y, pancolitis: 45%, inflammation grade: 2.59+/-0.92, P<0.05 for all comparisons). The incidence rate of absolute and relative rectal sparing (27.5%) and of patchy inflammatory disease proximal to the rectum (5.7%) was not significantly different between the UC-PSC cases and the UC controls (25% and 7.9%, respectively). UC-PSC patients had a higher prevalence rate of ileitis (35.7%) and pouchitis (42.8%), but the values were not significantly different from controls (26.9% and 26.6%, respectively). The incidence rate of dysplasia was similar between the 2 patient groups.

Conclusions: UC patients with PSC show a propensity for more extensive, but less active, disease but are otherwise characterized by similar pathologic findings compared with UC patients without PSC. Rectal sparing and patchy disease activity is not characteristic of UC patients with PSC.