Clinical features and comprehensive diagnosis of autoimmune pancreatitis in China

To search for the key factors of autoimmune pancreatitis (AIP) in China and to improve the early identification of AIP in order to avoid misdiagnosing it as pancreatic carcinoma.

Clinical, imaging, laboratory, and pathological data about AIP were collected and analyzed from 1996 to 2011 in The Chinese People's Liberation Army General Hospital.

A total of 33 patients (male 29, female 4) aged 35-76 years (52.3 ± 9.3 years) meeting the International Consensus Diagnostic Criteria for type 1 (n = 32) or type 2 (n = 1) AIP were included. With improved understanding of AIP, the misdiagnosis rate and unnecessary laparotomy rate was decreased from 95.7% (22/23) and 91.3% (21/23) before 2006, to 20.0% (2/10) (p = 0.001) and 0.0% (p = 0.001) respectively after 2006. The major symptoms were jaundice in (24/33, 72.7%) and abdominal pain (12/33, 36.4%). Half of the patients had other accompanied autoimmune disorders. Laboratory tests showed an elevated level of serum IgG in 9 out of 11 patients (81.8%) and an increased eosinophil count in 16 out of 33 patients (48.5%). The serum IgG4 levels were twice the upper limit of the normal value. CT scan showed a low-contrast margin characterized by a capsule-like rim in 24 of 32 patients (75.0%). Pathologic examinations showed fibrosis and infiltration of massive lymphocytes and plasma cells in the pancreas. Prednisone was given to the patients and proved to be quite effective for all of them (12/12, 100%).

Type 1 AIP shows a sex predilection compared with type 2 AIP in China. In order to diagnose AIP exactly, a comprehensive strategy, especially including imaging and pathological examination, should be used. With growing awareness, fewer AIP patients with this diagnosis would be misdiagnosed and incorrectly treated.