Autoimmune pancreatitis (AIP) remains little known. It is part of the differential diagnosis of acute non-alcoholic, non-biliary pancreatitis. The clusters of arguments in favor of type 1 AIP diagnosis are the clinical profile (male aged 50-70), the imaging (diffusely enlarged, “sausage-like”, pancreas), the elevation of serum IgG4 beyond the threshold of 135 mg/dl, the histological criteria and the disease corticosensitivity. Type 1 AIP is a component of the systemic IgG4 disease. Lymphadenopathies, pancreatitis and tubulointerstitial nephritis are the most frequent pathologies occurring in IgG4 disease. The evolution is often favorable following treatment with corticosteroids. Given the risk of relapse, a follow-up is necessary. The purpose of this article is to highlight the major elements leading to the diagnosis and treatment of type 1 AIP.
Key Words
Acute pancreatitis, type 1 autoimmune pancreatitis, IgG4-related systemic disease (IgG4-RSD), diagnosis criteria, treatment
What is already known about the topic?
Type 1 autoimmune pancreatitis is characterized by fibrosing and inflammatory pancreatic involvement associated to specific elevation of serum IgG4, and potential damages to other organs. The infiltration of several organs by IgG4 + plasma cells is what defines the diagnosis of IgG4-related systemic disease (IgG4-RSD). The diagnosis of AIP 1 is easily evoked in the presence of an enlarged sausage-like pancreas and elevation of serum IgG4 level> 135 mg. Given the heterogeneity of cases, the International Consensus Diagnostic Criteria established by an international consensus in 2011 allow to standardize the diagnosis based on 5 criteria: pancreatic parenchymal and ductal imaging, serological criteria, involvement of other organs, histological pancreatic criteria and positive response to corticotherapy. The criteria differentiate the levels of evidence 1 and 2.
What does this article bring up for us?
Based on an atypical and rare clinical case, this article summarizes the etiological assessment of acute pancreatitis of indeterminate cause and facilitates the recognition as well as the management of type 1 autoimmune pancreatitis, one of the manifestations of IgG4-RSD. Key Words Acute pancreatitis, type 1 autoimmune pancreatitis, IgG4-related systemic disease (IgG4-RSD), diagnosis criteria, treatment