IgG4-Related Sclerosing Cholangitis, a Rare Differential Diagnosis for a Common Clinical Presentation: A Case Report

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is a rare immune-mediated fibroinflammatory disease that represents a significant diagnostic challenge, as it may closely mimic malignant biliary neoplasms, particularly cholangiocarcinoma (CCA).

This report describes a 71-year-old man with a history of cholecystectomy for acute calculous cholecystitis who presented with new-onset obstructive jaundice. Magnetic resonance cholangiopancreatography demonstrated parietal thickening of the common hepatic duct at the confluence of the right and left hepatic ducts, associated with diffusion restriction and intrahepatic biliary dilatation. Serum CA 19-9 was markedly elevated, even after biliary drainage and endoluminal biopsies were inconclusive. Given the strong suspicion of perihilar CCA, the patient underwent right hepatectomy extended to segment 1 with extrahepatic bile duct resection and Roux-en-Y hepaticojejunostomy. Definitive histopathological examination revealed IgG4-SC involving both extrahepatic and intrahepatic bile ducts, without evidence of malignancy.

Isolated IgG4-SC remains a major diagnostic challenge because its clinical, biochemical, endoscopic, and radiological features may closely mimic CCA. This case highlights the limitations of current preoperative diagnostic tools and emphasizes the importance of considering IgG4-SC in the differential diagnosis of isolated biliary strictures. Although earlier assessment of serum IgG4 may broaden the diagnostic workup, definitive diagnosis may still only be achieved on histopathological examination. When malignancy cannot be confidently excluded, surgical resection remains an appropriate and often unavoidable management strategy.