Primary sclerosing cholangitis and IBD

The association between primary sclerosing cholangitis (PSC) and IBD is well documented, and the IBD in these cases may represent a distinct disease phenotype. Up to 90% of patients with PSC have IBD, usually ulcerative colitis (UC), while IBD is accompanied by PSC in approximately 5% of IBD patients. In PSC/UC patients, a distinct human leukocyte antigen genotype has recently been reported, while another study has identified UC susceptibility loci associated with PSC. Clinically, patients with UC that is associated with PSC often have a quiescent course with colitis characterized endoscopically by total colonic involvement with more right-sided colitis, rectal sparing, and backwash ileitis. There is also a high risk of pouchitis after colectomy. Histopathological examination of the colonic mucosa is needed for accurate assessment of UC activity. Several studies have shown that PSC/UC patients have a higher risk of developing colonic neoplasia, particularly of the right colon. Hence, total colonoscopy with "blind biopsies"rather than sigmoidoscopy should be used for surveillance in PSC/UC patients. The protective role of ursodeoxycholic acid against the development of colonic neoplasia needs further evaluation in this group of patients. Finally, among PSC/UC patients, those with severe liver disease seem to have a milder course of UC and lower risk of colorectal neoplasia compared with those with mild liver involvement. All of these aspects are reviwed in detail in this article.