Clinicopathological differentiation between sclerosing cholangitis with autoimmune pancreatitis and primary sclerosing cholangitis

Background. The present study was undertaken to identify the clinicopathological differences between sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) and primary sclerosing cholangitis (PSC). Methods. We retrospectively compared the clinical, cholangiographic, and liver biopsy findings between 24 cases of PSC and 24 cases of SC-AIP. Results. Patient age at the time of diagnosis was significantly lower in the PSC group than in the SC-AIP group. The peripheral blood eosinophil count was significantly higher in the PSC group than in the SC-AIP group, but the serum IgG4 level was significantly higher in the SC-AIP group. Cholangiography revealed band-like strictures, beaded appearance, and pruned-tree appearance significantly more frequently in PSC, whereas segmental strictures and strictures of the distal third of the common bile duct were significantly more common in SC-AIP. Liver biopsy revealed fibrous obliterative cholangitis only in the PSC specimens. No advanced fibrous change corresponding to Ludwig's stages 3 and 4 was observed in any of the SC-AIP specimens. IgG4-positive plasma cell infiltration of the liver was significantly more severe in SC-AIP than in PSC. Subsequent cholangiography showed no improvement in any of the PSC cases, but all SC-AIP patients responded to steroid therapy, and improvement in the strictures was observed cholangiographically. Conclusions. Based on the differences between the patients' ages and blood chemistry, cholangiographic, and liver biopsy findings, SC-AIP should be differentiated from PSC.