Ulcerative Colitis with and without Primary Sclerosing Cholangitis: Two Different Diseases?

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown origin and an important hepatobiliary complication of inflammatory bowel diseases (IBD), especially ulcerative colitis (UC). When further differentiated, about 3-8% of UC patients suffer from PSC, whereas among Crohn's disease patients the reported prevalence of PSC is probably between 1 and 3.5%. Although it was reported from Japan that the frequency of PSC in UC was only 34%, the same registry data indicated that the prevalence was up to 57% among young patients with PSC even in Japan, which is comparable to the 60-80% in Europe and the US. Additionally, the clinical features of UC in patients with PSC are different from those in patients without PSC, for instance, rectal sparing and right-sided dominance.

The strong link between atypical IBD and PSC suggests that the pathogenesis of PSC involves pathology of the gut, including abnormal gut microbiota and aberrant activation of mucosal lymphocytes. These seem to be different in UC PSC as compared to the pathology of typical UC.

The key to solving the question 'Is there a difference between East and West?' are genetic studies, genome-wide association studies of PSC in particular, which have already been performed in the West and are strongly warranted in the East.