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IgG4‐related sclerosing cholangitis without obvious pancreatic lesion: Difficulty in differential diagnosis

Autoimmune pancreatitis (AIP) is a well-known disorder, and guidelines for its diagnosis and management are available for daily clinics. The identification of AIP based on clinical manifestations, serum markers and histological findings is crucial for accurate diagnosis. In addition to the standard diagnostic processes, endoscopic ultrasonography-guided fine needle aspiration biopsy (EUS-FNA) and steroid therapy allow the exclusion of pancreatic malignancy. Typical extra-pancreatic lesions depicted by systemic image scanning are also clues for the diagnosis of AIP. The biliary tract is the most frequent target of immunoglobulin G4 (IgG4)-related systemic disease, namely AIP-associated sclerosing cholangitis (AIP-SC) or IgG4-related sclerosing cholangitis (IgG4-SC) accompanied by AIP.