In this compact review, we clarify the disease of IAC, summarize criteria for diagnosis of IAC, discuss the role of CA 19-9, and provide key information to differentiate diagnosis of IAC from CCA. IAC should be highly suspected in unexplained biliary stricture associated with increased IgG4 (in serum especially in bile) and other organ involvement (kidney, retroperitoneum etc. especially pancreas in which there are abundant IgG4-positive

plasmocytes infiltration). Correct diagnosis of IAC will avoid unnecessary surgery because IAC responds well to steroid therapy. In a word, increased IgG4 levels, other organ involvement and response to steroids are keys to distinguishing IAC from Sotrastaurin CCA. In recent decades, autoimmune cholangitis (to IgG4) or immunoglobulin G4-associated cholangitis (IAC) has been identified see more worldwide.[1] The clinical, biochemical and imaging features of IAC mimic cholangiocarcinoma (CCA), making diagnosis difficult. Currently, the reports of IAC are rare except for some cases.[2, 3] Most of these few cases were misdiagnosed as CCA, and notably, unnecessary surgical resections were performed.[3-11] Early reports document cases of histological diagnoses of IAC after surgical

resection. Increasing knowledge about IAC is necessary. According medroxyprogesterone to reports and our experiences, a typical encounter between an IAC patient and doctor was as follows: A 50- to 60-year-old male complained of abdominal pain and weight loss. Physical examination showed subxiphoid area mild tenderness with or without jaundice. Laboratory assessments showed elevated serum amylase, urine amylase, or/and importantly serum carbohydrate antigen 19-9 (CA19-9). A variety of imaging findings, such as ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI), presented bile duct stricture. These

all made straightforward diagnoses of chronic pancreatitis and malignant bile duct carcinoma. Furthermore, Whipple’s operation was performed. Surprisingly, there were no tumor cells found in specimens even in the most abnormal parts, which looked like carcinomas. Then immunostaining of IgG4 was completed. The result showed a large amount of IgG4-positive stained cells infiltration in the bile duct (or/and in other involved organs, especially the pancreas, which would not have been examined earlier). The final diagnosis of IAC would be confirmed (and/or accompanied by other IgG-related disease, corresponding as Ig4 related autoimmune pancreatitis etc.). The lesson from the above case is that IAC shares a number of clinical, biochemical, imaging features with CCA and is often misdiagnosed as CCA.