[Role of Imaging in Autoimmune Pancreatitis]

Autoimmune pancreatitis is a specific form of chronic recurrent pancreatitis whose etiopathogenesis involves immunological mechanisms. Historically, two varieties of the disease have been described, each with clinical, biochemical and histological particularities. Recently, a third subtype has been described as a consequence of the adverse effects associated with immunotherapy, which is increasingly indicated for several tumors. The diagnosis of autoimmune pancreatitis is a challenge for professionals, in part because of its heterogeneous clinical presentation, which includes obstructive jaundice in type 1 autoimmune pancreatitis and abdominal pain in type 2, and can mimic more serious pathologies such as pancreatic ductal adenocarcinoma. Serum biomarkers (IgG4) play an important role in the diagnosis, but they can sometimes be normal, especially in type 2 autoimmune pancreatitis, or be elevated in other pathologies. Non-invasive imaging techniques, in particular magnetic resonance cholangiopancreatography with intravenous contrast, play a central role in the diagnostic process of the disease. In this article, we review the imaging aspects of autoimmune pancreatitis and the extrapancreatic manifestations of systemic IgG4 disease, the features that differentiate it from pancreatic cancer and we evaluate the radiological criteria for response to corticosteroid treatment.