1. TSA016
Rare Autoimmune Cholangitis which Mimics an Extrahepatic Cholangiocarcinoma
Guo-Zhi Wang, Ting-Yen Huang, Yu-Ying Wu, Yu-Bing Lim, Chia-Chun Hung, Li-Chuan Ting, Su-Chin Tsao, Hsiang-Lin Lee
A 67-year-old woman, history: hypertension
Abdominal cramping pain, tea-colored urine, body weight loss by 3 kg within 2 weeks
Elevated direct bilirubin level
Abdominal Sonography, CT, and ERCP => CHD eccentric stricture with IHD dilatation => Contrast-enhancing lesion at the confluence of bilateral hepatic ducts
: Bilirubin 9.1 mg/dL, direct 5.7; CA19-9, CEA, AFP all WNL
=>ERCP, EST, stent
: Bilirubin 2.7
: Bilirubin 1.2
: ANA(+) (0525報告), Anti-HCV (+); IgG4 198 mg/dL (0524報告)
: IgG4 131 mg/dL

2. Histopathology and Serum Antibody Level
Suspected to be Cholangiocarcinoma => Left hepatectomy + Roux-en-Y anastomosis
Histopathology and Serum Antibody Level
Pathology report: No malignancy
Infiltrations with lymphocytes, IgG4+ plasma cells, and eosinophils
"Storiform" fibrosis
Obliterative phlebitis
The optimal cut-off value of serum IgG4 for a diagnosis of IgG4-RD was 144 mg/dL, and the sensitivity and specificity were and 90.76%, respectively. Levels of serum IgG4 were elevated in IgG4-RD, Churg-Strauss syndrome, multicentric Castleman's disease, eosinophilic disorders, and in some patients with rheumatoid arthritis, systemic sclerosis, chronic hepatitis, and liver cirrhosis. The usual cut-off value of 135 mg/dL in AIP is useful for diagnosing whole IgG4-RD, but high levels of serum IgG4 are sometimes observed in not only IgG4-RD but also other rheumatic and common diseases. ~2012 Yamamoto M. Mod Rheumatol.
Elevated serum IgG4 levels 198 mg/dL (pre-operative)
Tumor markers within normal limits
IgG4-related sclerosing cholangitis

3. IgG4 related diseases (IgG4-RD)
Immune disorder: Granulation, fibrosis, and mass formation
Manifestations of various sites: Type 1 autoimmune pancreatitis (AIP), Mikulicz disease (salivary gland), etc. …
Most patients respond to glucocorticoids, the 1st-line treatment for remission induction
Steroid-sparing agents may be considered if relapse
Our patient, with daily prednisolone, no evidence of relapse nor IgG4-RD of other organs
2015 International Consensus Guideance Statement on the Management and Treatment of IgG4-Related Disease
Conclusion
IgG4-RD can mimic neoplasms, granulomatosis, and other diseases. Careful distinguishing is essential