Background: Overlap syndrome is a term used for overlapping features of autoimmune hepatitis and primary sclerosing cholangitis or primary biliary cirrhosis and for autoimmune cholangitis. We describe a high prevalence of small duct primary sclerosing cholangitis among patients with overlapping autoimmune hepatitis and primary sclerosing cholangitis.
Methods: We sought to retrieve all patients with overlap syndrome between primary sclerosing cholangitis and autoimmune hepatitis in six university hospitals in Sweden. The revised autoimmune hepatitis scoring system proposed by the International Autoimmune Hepatitis Group was used to establish the diagnosis autoimmune hepatitis. Endoscopic retrograde cholangiography and/or magnetic resonance cholangiography were used to separate the primary sclerosing cholangitis cases diagnosed through liver biopsy into small and large primary sclerosing cholangitis. A histological diagnosis compatible with both autoimmune hepatitis and primary sclerosing cholangitis was required for inclusion.
Results: 26 patients fulfilled our criteria for histological overlap of autoimmune hepatitis and primary sclerosing cholangitis, 7 (27%) of which had small duct primary sclerosing cholangitis. The reliability of the diagnosis small duct primary sclerosing cholangitis was supported by a very close similarity between small and large duct primary sclerosing cholangitis patients in clinical and laboratory data, and by a poor response to immunosuppressive therapy in the small duct primary sclerosing cholangitis patients. Patients with large duct overlap syndrome had a good response to immunosuppressive therapy. In both groups, our limited experience from ursodeoxycholic acid was largely poor.
Conclusions: Small duct primary sclerosing cholangitis is prevalent in the overlap syndrome between autoimmune hepatitis and primary sclerosing cholangitis.