Abstract
IgG4-related cholangitis (IRC) is a chronic cholestatic liver disease that often occurs concomitantly with autoimmune pancreatitis type 1. Both conditions are manifestations of IgG4-related disease, a systemic autoimmune-mediated fibroinflammatory disorder. Patients often present with jaundice and weight loss, mimicking hepatobiliary malignancies, such as cholangiocarcinoma, primary sclerosing cholangitis, and pancreatic cancer. Accurate diagnosis is challenging due to the absence of pathognomonic findings but can be achieved using the HISORt criteria (histology, imaging, serology, other organ involvement, and response to immunosuppressive therapy). Early diagnosis is critical to avoid unnecessary surgery and prevent progression to liver fibrosis or cirrhosis. IRC responds well to corticosteroid therapy, though relapses are common, necessitating long-term immunosuppressive treatment in many cases. Steroid-sparing agents for remission induction and maintenance therapy comprise immunomodulators, such as azathioprine, as well as B-cell depletion therapies, such as rituximab. This review provides a structured clinical overview of the diagnosis, differential diagnosis, and therapy, including novel therapeutic options, such as inebilizumab, for this rare yet severe condition. A key focus is on long-term surveillance strategies, which include laboratory tests, imaging (contrast-enhanced magnetic resonance imaging/magnetic resonance cholangiopancreatography, ultrasound, endosonography), and, particularly in patients with fibrotic bile duct strictures, endoscopy (endoscopic retrograde cholangiopancreatography, cholangioscopy).