Distinct phenotype of primary sclerosing cholangitis-associated inflammatory bowel disease.

Primary sclerosing cholangitis (PSC) is frequently accompanied by colitis with clinicopathologic features that differ from conventional inflammatory bowel disease (IBD). Accumulating evidence indicates that PSC-associated IBD (PSC-IBD) often presents as extensive colitis with a right-sided predominant distribution and characteristic endoscopic features, such as rectal sparing and backwash ileitis. Beyond endoscopic appearance, PSC-IBD also appears to have distinct biological underpinnings, including shared genetic susceptibility, dysregulated bile acid signaling, altered gut microbial communities, and immune crosstalk along the gut-liver axis. These mechanisms may contribute not only to intestinal inflammation but also to PSC-related clinical outcomes. From a long-term perspective, patients with PSC and colitis are consistently classified as a high-risk group for colorectal neoplasia, warranting early and intensive colonoscopic surveillance. In parallel, surveillance for hepatobiliary malignancies remains central in PSC care, although risk stratification continues to evolve. Therapeutic management generally follows established IBD algorithms, yet the extent to which colitis-directed therapies modify PSC outcomes remains uncertain, with heterogeneous findings across cohorts and endpoints. In this review, we summarize current knowledge on the clinical phenotype, mechanistic framework, and outcome-driven management of PSC-IBD, and highlight future directions toward precision surveillance and mechanism-based interventions targeting bile acid-microbiota-immune interactions.