Of these, 15 fulfilled HISORt and Asian criteria for the diagnosis of IgG4-related diseases

Of these, 15 fulfilled HISORt and Asian criteria for the diagnosis of IgG4-related diseases. in 1412 patients and clinical diagnoses were recorded from a review of patient charts. The prevalence of AIP or IAC in the entire cohort was 1.1% (n= 15). The sensitivity of IgG4for the diagnosis of AIP and IAC was 80% and the specificity was 86% at a cut-off value of 135 mg/dl. The positive predictive value and the negative predictive value were 6% and 99.7%, respectively. The most common differential diagnosis in patients with elevated IgG4was liver cirrhosis. == Conclusion == IgG4has a reasonable sensitivity and specificity in a liver and pancreas clinic population, where liver cirrhosis appears to be the most frequent differential diagnosis for elevated IgG4concentrations. Keywords:pancreatitis, cholangitis, malignancies, diagnostic performance, cirrhosis == Introduction == Immunoglobulin subclass 4 (IgG4)-associated diseases are an increasingly recognized group of autoimmune diseases,1,2which are characterized by sclerosis and lymphoplasmocytic infiltration of affected organs with IgG4-positive cells.25The disease can affect the pancreas, biliary tract, salivary glands, retroperitoneum, lymph nodes, kidney, lungs or the prostate.6,7In the gastrointestinal tract, autoimmune pancreatitis (AIP) and IgG4-associated cholangitis (IAC) are considered the most common manifestations.8 The prevalence of AIP ranges from 4% to 8% among patients with pancreatitis in different study cohorts.9Common differential diagnoses of AIP and IAC NP include chronic pancreatitis, pancreatic cancer and primary sclerosing cholangitis.1,10,11Male predominance and a mean age of 60 10 years were consistently reported.5,6,12,13Clinicopathological and radiological features include jaundice, abdominal pain, and diabetes mellitus, extra and intrahepatic biliary strictures, pancreatic duct Aldose reductase-IN-1 encasement and a sausage shape of the pancreas on abdominal magnetic resonance imaging (MRI) or computed tomography (CT).1,5,6,13 Studies on IgG4-related diseases were predominantly carried out in Asian countries,1416the United States of America5and Europe,9,17where different diagnostic criteria for AIP have been proposed by several societies. The Japanese and Korean criteria were established in 2006 and 2007, respectively.15,16The HISORt criteria (Histology,Imaging,Serology,Other organ involvement,Response totherapy) were proposed by Chariet al. in 2006.5 The typical histological finding of IgG4-related diseases is infiltration of affected organs with IgG4-positive plasma cells.5,15,16Imaging studies in patients with IAC or AIP show irregular narrowing of the bile ducts or the pancreatic duct by endoscopic retrograde cholangiopancreaticography (ERCP), and enlargement of affected organs or pseudotumour formation. Elevated serum IgG4and autoantibodies (ANA and RF) are commonly found in serological studies.1,5,9,15,16More specific antibodies directed against carbonic anhydrase II, SPINK1 or trypsinogen have been identified.18The performance of total IgG4serum concentrations for the diagnosis of IgG4-related diseases has been evaluated in different studies. A cut-off for IgG4elevation was suggested at 135 mg/dl by Hamanoet al. in 2001 with Aldose reductase-IN-1 a sensitivity of 95% and a specificity of 97%.4The Mayo Clinic group reported a specificity and a sensitivity of 93% and 76%, respectively, at a cut-off level of >140 mg/dl. In patients with IgG4concentrations >280 mg/dl, a sensitivity of 53% and a specificity of 99% was found.5Based on these findings, the IgG4serum concentration has been proposed as a non-invasive parameter for the diagnosis of IgG4-related disease and is included in the HISORt criteria. The aim of the present Aldose reductase-IN-1 study was to evaluate the sensitivity and specificity of a serum IgG4concentration in an unselected liver and pancreas clinic population. == Patients and methods == From January 2009 to May 2010, serum immunoglobulin subclasses were prospectively determined in all patients referred to the unit of gastroenterology and hepatology at the Medical University Innsbruck, Austria. To record clinical diagnoses, patients’ charts were carefully reviewed and a diagnosis of AIP and AIC was made according to the HISORt and ASIAN criteria. IgG4concentrations were determined in patients’ sera using the immunoglobulin subclass assay from Siemens N IGG4 Aldose reductase-IN-1 (formerly Dade Behring, Marburg, Germany) on a Behring Nephelometryplatform (BN II). The interassay coefficients of variation were 3.7% at 0.195 g/l, 2.4% at 0.507 g/l and 3.5% at 0.729 g/l, respectively. == Statistical analysis == Results are shown as absolute numbers and.