Clinical characteristics of IgG4-related autoimmune pancreatitis and its diagnostic strategy evaluation

Abstract

Objective To investigate the clinical characteristics and diagnosis of IgG4-related autoimmune pancreatitis (IgG4-AIP). Methods Clinical data of 24 IgG4-AIP patients admitted toSun Yat-sen Memorial Hospital Affiliated to Sun Yat-sen University from January 2013 to December 2018 were retrospectively analyzed. The informed consents of all patients were obtained and the local ethical committee approval was received. Among them, 20 patients were male and 4 female, aged 46-84 years with a median age of 61 years. Patients with IgG4-AIP were diagnosed according to the comprehensive diagnostic criteria of IgG4-related disease (IgG4-RD) and the International Consensus Diagnostic Criteria (ICDC).Its clinical manifestations, laboratory, imaging, pathological examinations and the diagnostic strategy were analyzed. Results Clinical manifestations included abdominal pain in 12 cases, jaundice in 10, abdominal distension in 6, emaciation in 3 and no symptoms in 2, respectively. 7 patients were diagnosed with simple pancreatic lesions and the remaining cases were complicated with 1-5 organs involvement, which were biliary tract involvement in 10 cases, lymph nodes in 8 cases, salivary glands in 3 cases, lungs in 3 cases, gastrointestinal tract in 2 cases, blood vessels in 2 cases, and liver, eye, retroperitoncum in 1 case, respectively. The median level of serum IgG4 was 18(2-117) g/L. Imaging examination indicated localized pancreatic masses in 13 cases, diffuse swelling in 11 cases and pancreatic duct stenosis in 9 cases, respectively. Pathological examination of the pancreas demonstrated fibrosis in 4 cases, IgG4+ cell count>10/high power field, and IgG4+/IgG+> 40% in 12 cases. According to comprehensive diagnostic criteria of IgG4-RD, 10 cases were diagnosed withIgG4-AIP and 14 cases were diagnosed with IgG4-AIP according to ICDC. 8 cases were misdiagnosed as pancreatic head cancer or cholangiocarcinoma. Pancreatic resection or biopsy was performed and the postoperative pathological examination confirmed the diagnosis of IgG4-AIP. Conclusions Clinical manifestations of IgG4-AIP are nontypical. The localized lesions are easy to be misdiagnosed. The diagnostic rate can be improved by comprehensive application of serum IgG4 detection, imaging and pathological examinations, and ICDC criteria. Key words: Pancreatitis; Clinical features; Diagnosis