Autoimmune cholangitis and cholangiocarcinoma

Area of Science:

• Gastroenterology
• Immunology
• Pathology

Background:

• Autoimmune cholangitis, or immunoglobulin G4-associated cholangitis (IAC), is a manifestation of IgG4-related disease.
• IAC presents as biliary strictures, often mistaken for cholangiocarcinoma (CCA).
• Misdiagnosis can lead to unnecessary surgical intervention for IAC.

Purpose of the Study:

• To clarify the characteristics of IAC.
• To summarize diagnostic criteria for IAC.
• To differentiate IAC from CCA, focusing on key diagnostic indicators.

Main Methods:

• Review of clinical, biochemical, and imaging features of IAC and CCA.
• Analysis of the role of carbohydrate antigen 19-9 (CA 19-9) in diagnosis.
• Identification of key differentiating factors between IAC and CCA.

Main Results:

• IAC shares features with CCA, leading to frequent misdiagnosis.
• Elevated serum IgG4 levels and IgG4-positive plasma cell infiltration in bile ducts are characteristic of IAC.
• Other organ involvement, particularly autoimmune pancreatitis, is common in IAC.

Conclusions:

• High suspicion for IAC is warranted in cases of unexplained biliary stricture with elevated IgG4 and other organ involvement.
• Distinguishing IAC from CCA is vital to guide appropriate treatment and avoid unnecessary surgery.
• Increased IgG4 levels, associated organ involvement, and steroid responsiveness are key to differentiating IAC from CCA.