Clinical Characteristics Of IgG4-related Autoimmune Pancreatitis

ObjectiveTo investigate the clinical characteristics of IgG4-related autoimmune pancreatitis（IgG4-AIP）.MethodsA retrospective analysis was performed on 61 patients with IgG4-AIP treated in The Affiliated Hospital of Qingdao University from 2013.1 to 2021.12.Demographic information,clinical symptoms,past medical history and personal history,laboratory testing,imaging,histopathology,treatment and prognosis were collected.Patients who underwent surgery were excluded and those who chose to apply hormone therapy were included.The patients were divided into two groups according to whether they had recurrence,and their clinical manifestations,serological tests and treatment methods were compared to find the risk factors for recurrence of IgG4-AIP.SPSS24.00 software was used for statistical analysis.The measurement data of normal distribution were expressed as（?）±s,the comparison between the two groups was performed by t test,the measurement data of non-normal distribution was expressed by M（Q₁^Q₃）,and the comparison between the two groups was performed by Mann-Whitney U test.Counting data is expressed in percentage.Log-rank test was used for survival analysis.P<0.05 was statistically significant.The cumulative recurrence rate was calculated by Kaplan-Meier method.ResultsThe number of newly diagnosed cases of IgG4-AIP showed an increasing trend,the male to female ratio was 5.8:1,the average age was 60.4±10.7 years,and the predilection age was 50-69 years.The most common clinical symptoms were jaundice（47.5%,29/61）,abdominal pain in 23 cases（37.7%）,weight loss in 22 cases（36.1%）,physical examination in 10 cases（16.4%）,pruritus in 7 cases（11.5%）,and acute pancreatitis in 7 cases（11.5%）.Twelve patients（19.7%）were admitted to the hospital for suspected"pancreatic and bile duct malignant tumor".Other organs were involved in 85.2%（52/61）IgG4-AIP patients.The most common extrapancreatic manifestations of IgG4-AIP were bile duct involvement（70.5%,43/61）,followed by salivary glands in 11 cases（18.0%）,eyes in 6 cases（9.8%）,lymphadenopathy in 6 cases（9.8%）,retroperitoneal fibrosis in 1 case（1.6%）,and stomach in 1 case（1.6%）.There were 39 patients（63.9%）with single organ involvement,9 patients（14.8%）with 2 organs involvement,and 4 patients（6.5%）with 3 organs involvement.Serum IgG4 was elevated in 58 patients（95.1%）,and higher than 2 times the upper limit of normal in 51 patients（83.6%）.48 patients（78.7%）showed abnormal liver function,among which the increase of glutamyltransferase（43/61,70.5%）was the most significant,followed by alanine aminotransferase（40/61,65.6%）,alkaline phosphatase（37/61,60.7%）,direct bilirubin（37/61,60.7%）,total bilirubin（35/61,57.4%）and glutamic oxalacetic transaminase（32/61,52.5%）.Dyslipidemia occurred in 19 patients（37.3%）.Radiographically,40 cases（65.6%）had diffuse pancreatic enlargement,and 21 cases（34.4%）were focal pancreas.Among the focal occupying patients,pancreatic head involvement was the most common（11/21,52.4%）,pancreatic tail involvement in 8 cases（38.1%）,pancreatic tail involvement in 1 case（4.8%）,and pancreatic head involvement in1 case（4.8%）.18 patients（29.5%）underwent endoscopic ultrasonography,and 8 patients（13.1%）underwent fine needle puncture guided by endoscopic ultrasonography.No definite malignant tumor cells were found.Only 1 patient had fibrosis and a very small amount of lymphoplasmic cell infiltration,and a small number of plasma cells showed IgG4（+）.Surgical resection was performed in 1 of 61 patients.Sixty patients were treated with prednisone（20-35mg/d）or methylprednisolone（20-40mg/d）during the induction remission period,and continued treatment for 2-4 weeks until effective remission,then gradually reduced the value of small doses（prednisone 5mg/d,methylprednisolone 4mg/d）into maintenance therapy.Thirty-two patients were treated with the immunosuppressant cyclophosphamide during the dosing reduction period.All 61 patients were followed up for a median follow-up period of 33 months（range 4-96 months）until December 2021.Fourteen patients（23.0%）relapsed,with a median time of 20 months（range 5-63 months）.Among patients who relapsed,the recurrence rate was 57.1%within 1 year,64.3%within2 years,71.4%within 3 years,and 92.9%within 5 years.In Kaplan-Meier curves,the overall recurrence rates at 1,3 and 5 years were 12.7%,15.4%and 35.8%,respectively.Excluding surgical patients,univariate Log-rank analysis was performed between the recurrence group and the non-recurrence group,and no significant differences were found in gender,clinical symptoms,the other organ involvement,serum IgG4,location of pancreatic enlargement and treatment methods.However,the 3-year recurrence rate of IgG4-AIP patients treated with hormone combined with cyclophosphamide was 6.7%,and the 3-year recurrence rate of IgG4-AIP patients treated with hormone alone was 17.4%.The 3-year recurrence rate of IgG4-AIP patients treated with hormone combined with cyclophosphamide was significantly reduced.Conclusions1.The number of newly diagnosed cases of IgG4-AIP is generally on the rise every year,and most of them occur in males over 50 years old,with the highest incidence in 50-69 years old.The main clinical symptoms were jaundice,followed by abdominal pain and weight loss.2.Extrapancreatic organs are often involved in IgG4-AIP patients,and the bile duct is the most commonly involved site.3.The use of EUS-FNA for pathological examination of the lesion site is conducive to the differential diagnosis of IgG4-AIP and pancreatic cancer.4.The 3-year recurrence rate of IgG4-AIP was 15.4%.Compared with hormone alone,hormone combined with cyclophosphamide could reduce the 3-year recurrence rate.Extrapancreatic involvement and serum IgG4 increased more than 2 times the upper limit of normal value,and pancreatic diffuse enlargement may not be a risk factor for recurrence.