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 20170503: Bilirubin 9.1 mg/dL, direct 5.7; CA19-9, CEA, AFP all WNL =>ERCP, EST, stent 20170508: Bilirubin 2.7 20170510: Bilirubin 1.2 20170522: ANA(+) (0525報告), Anti-HCV (+); IgG4 198 mg/dL (0524報告) 20180122: IgG4 131 mg/dL

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 95.10 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

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