| Objective: To investigate the clinical role of serum immunoglobulin(Ig)G4 level in the differential diagnosis of type I autoimmune pancreatitis(AIP)and pancreatic diseases,utilize serum Ig G4 to differentiate focal type I autoimmune pancreatitis from pancreatic cancer or pancreatic cancer with elevated serum Ig G4(serum Ig G4>2.01g/L as elevated serum Ig G4 level),and improve the accuracy of type I autoimmune pancreatitis diagnosis and reduce its misdiagnosis rate.Methods:A retrospective analysis was performed for the complete data from 70 cases with type I autoimmune pancreatitis,309 cases of pancreatic cancer,62 cases of chronic pancreatitis(excluding autoimmune pancreatitis)and 24 cases of acute pancreatitis with serum Ig G4 test admitted in Hunan Province People’s Hospital from June 2015to June 2020.The serum Ig G4 level was determined by using immunoturbidimetry for the patients.The serum Ig G4 levels and the proportions of increased serum Ig G4 were compared between groups.The serum Ig G4 was also compared in the type I autoimmune pancreatitis group.Receiver operating characteristic(ROC)curve analysis was carried out to analyze the ability of serum Ig G4 level in differential diagnosis between type I autoimmune pancreatitis and other pancreatic diseases,focal type I autoimmune pancreatitis and pancreatic cancer,focal type I autoimmune pancreatitis and pancreatic cancer with elevated serum Ig G4.The area under curve(AUC)was calculated to determine the optimal critical value.Results:In the type I autoimmune pancreatitis group,pancreatic cancer group,chronic pancreatitis group and acute pancreatitis group,the serum Ig G4 levels were(10.7 ± 7.5)g/L,(0.9 ± 0.6)g/L,(0.6 ± 0.3)g/L and(0.6 ± 0.4)g/L,respectively,and the proportions of increased serum Ig G4 were 100%,5.2%,0 and 0,respectively.The serum Ig G4 level and the proportion of increased Ig G4 in type I autoimmune pancreatitis group were significantly higher than those in the other three groups(all P<0.05),among which no difference in the serum Ig G4 level or the proportion of increased Ig G4 was observed(all P>0.05).In type I autoimmune pancreatitis group,no difference was observed in serum Ig G4 level between diffuse type I autoimmune pancreatitis group and focal type I autoimmune pancreatitis group(12.4 ± 8.0 g/L vs.9.3 ± 6.8 g/L,P>0.05),or between obstructive jaundice group and non-jaundice group(11.6 ±7.6 g/L vs.8.7 ± 7.0 g/L,P>0.05).However,the serum Ig G4 levels were higher in patients with extrapancreatic organ involved those in patients without extrapancreatic organ involved(15.3 ± 8.6 g/L vs.9.1 ± 6.4 g/L,P<0.05).ROC curve analysis showed that for differential diagnosis between type I autoimmune pancreatitis and other pancreatic diseases,the AUC of serum Ig G4 was was 0.999(0.997-1.000),the optimal critical value was 2.03g/L,and the differential diagnosis showed 100%sensitivity 、 96.2% specificity and 98.1% accuracy.For differential diagnosis between focal type I autoimmune pancreatitis and pancreatic cancer,the optimal critical value of type I autoimmune pancreatitis was2.07g/L,the AUC was 0.997(0.993-1.000),and the differential diagnosis showed 97.4% sensitivity 、 95.1% specificity and 96.3% accuracy.For differential diagnosis between focal type I autoimmune pancreatitis and pancreatic cancer with elevated serum Ig G4,the AUC of serum Ig G4 was2.93g/L,the AUC was 0.940(0.876 ～ 1.000),and the differential diagnosis showed 86.8% sensitivity 、 93.7% specificity and 90.3%accuracy,respectively.Conclusions:1.For clinical diagnosis of type I autoimmune pancreatitis,the increased serum Ig G4 has important reference role for clinical diagnosis.2.For screening pancreatic diseases,type I autoimmune pancreatitis shall be considered when serum Ig G4>2.03g/L.While for patients with localized pancreatic mass,the possibility of pancreatic cancer with elevated serum Ig G4 shall be considered when serum Ig G4 is in the range of 2.07-2.93g/L,and puncture and biopsy shall be carried out when necessary.When serum Ig G4>2.93g/L,consider the possibility of focal type I autoimmune pancreatitis,which has certain clinical practicability. |
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