A Case of Autoimmune Cholangitis Misdiagnosed for Cholangiocarcinoma: How to Avoid Unnecessary Surgical Intervention?

INTRODUCTION Autoimmune cholangitis or immunoglobulin G4-associated cholangitis (IAC) has been recently regarded as a new clinical and histopathological entity and is a part of a complex autoimmune disorder--IgG4-related systemic disease (ISD). ISD is an autoimmune disease with multi-organic involvement, characterized with IgG4-positive plasmocytic infiltration of various tissues and organs with a consequent sclerosis, which responds well to steroid therapy. Most commonly affected organs are the pancreas (autoimmune pancreatitis, [AIP]) and the common bile duct (IAC). IAC and cholangiocarcinoma (CCA) share many clinical, laboratory and imaging findings. CASE OUTLINE We present a case of a 60-year-old male with a biliary stricture of a common bile duct, which was clinically considered as a bile duct carcinoma and treated surgically. Definite histopathological findings and immunohistochemistry revealed profound chronic inflammation, showing lymphoplasmacytic IgG-positive infiltration of a resected part of a common bile duct, highly suggestive for the diagnosis of IAC. In addition, postoperative IgG4 serum levels were also increased. CONCLUSION It is of primary clinical importance to make a difference between IAC and CCA, in order to avoid unnecessary surgical intervention. Therefore, IAC should be considered in differential diagnosis in similar cases.