Why is PSC considered an EIM of IBD, and how does it behave

What is known

- About 80% of PSC patients have concurrent IBD, and PSC is described as one of its extraintestinal manifestations, more specifically linked with ulcerative colitis. ^1,2 - The clinical course of hepatobiliary manifestations like PSC does not always correlate with disease activity and can be independent of the degree of intestinal inflammation, reflecting a shared pathogenesis. ³ - Liver disease activity does not parallel bowel inflammation, and PSC can develop de novo after colectomy. ⁴ - PSC is a chronic, progressive cholestatic/fibro-proliferative disease of intrahepatic and/or extrahepatic bile ducts, with most patients eventually developing cirrhosis and malignancy risk. ^1,5 - The strong PSC-IBD association is found in nearly all published cohorts worldwide, prompting some to prefer the term colitis-associated sclerosing cholangitis. ⁶

What is unknown / caveats

- Exact mechanisms linking PSC and IBD are still not fully understood ¹ - Much of the longitudinal course data comes from retrospective childhood-onset cohorts with acknowledged limitations ^7,8 - The precise shared pathogenic mechanism between PSC and IBD remains incompletely defined.

## References

1. Tang Q, Li L, Li Y, Yin W, Zhong X. Association between inflammatory bowel disease and primary sclerosing cholangitis: Insights from bibliometric analysis. Medicine (Baltimore). 2024. PMID: 38788011.

2. Sleiman J, Francis FF, Coelho-Prabhu N, Hashash JG. All you need to know about the overlap between primary sclerosing cholangitis and inflammatory bowel disease. Ann Gastroenterol. 2025;38:107-120. PMID: 40124424.

3. Uko V, Thangada S, Radhakrishnan K. Liver disorders in inflammatory bowel disease. Gastroenterol Res Pract. 2012. PMID: 22474447.

4. Grant Allister J, Lalor Patricia F, Salmi M, Jalkanen S, Adams David H. Homing of mucosal lymphocytes to the liver in the pathogenesis of hepatic complications of inflammatory bowel disease. Lancet. 2002;359:150-7. PMID: 11809275.

5. Palmela C, Peerani F, Castaneda D, Torres J, Itzkowitz SH. Inflammatory Bowel Disease and Primary Sclerosing Cholangitis: A Review of the Phenotype and Associated Specific Features. Gut Liver. 2018;12:17-29. PMID: 28376583.

6. Ponsioen CY. Diagnosis, Differential Diagnosis, and Epidemiology of Primary Sclerosing Cholangitis. Dig Dis. 2015. PMID: 26640943.

7. Nayagam JS, Mandour MO, Taylor A, Heneghan MA, Dubois PC, Hayee B, Lee HM, Vadamalayan B, Samyn M, Joshi D, Kent AJ. Clinical course of inflammatory bowel disease and impact on liver disease outcomes in patients with autoimmune sclerosing cholangitis. Clin Res Hepatol Gastroenterol. 2022;46(7):101980. PMID: 35728760.

8. Warner S, Rajanayagam J, Russell E, Lloyd C, Ferguson J, Kelly DA, Hirschfield GM. Biliary disease progression in childhood onset autoimmune liver disease: A 30-year follow-up into adulthood. JHEP Rep. 2024. PMID: 38235169.

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_Draft, generated by the IBDology RAG and not yet clinician-reviewed. Answers are grounded in the retrieved literature listed above; a high faithfulness score means the answer matches its sources, not that the sources are correct._