Recognition of other organ involvement might assist in the differential diagnosis of IgG4-associated sclerosing cholangitis without apparent pancreatic involvement: report of two cases.

IgG4-associated sclerosing cholangitis (IAC) was recently defined as biliary involvement of IgG4-related systemic disease. It is frequently associated with autoimmune pancreatitis, characterized by pancreatic enlargement and irregular narrowing of the pancreatic duct. However, a few cases of IAC with no apparent pancreatic involvement have been described, the characteristics of which may mimic those of cholangiocarcinoma. We report two rare cases of IgG4-associated sclerosing cholangitis at the hepatic hilum, mimicking hilar cholangiocarcinoma. When trying to establish the diagnosis, we should consider other organs that could be involved, such as the pancreas, salivary glands, retroperitoneum, lymph nodes, and kidneys, as well as chronic inflammatory changes. By recognizing these lesions and measuring serum IgG4, IAC can be diagnosed correctly, thereby avoiding unnecessary major surgery for a condition that is treated effectively by steroid therapy.