Pancreatic and biliary tract involvement in IgG4-related disease.

The diagnosis and treatment of pancreatic and biliary tract involvement in IgG4 disease can be challenging for physicians. A French series shows that the pancreas is the most frequently involved organ in systemic IgG4 disease. Pancreatitis may be found in more than 50% of patients with IgG4 disease and the biliary tract is involved in one third. Pancreatic or biliary involvement may be isolated, metachronous or synchronous of other IgG4-related organ injuries. Pancreatitis related to IgG4 disease is called autoimmune pancreatitis (AIP) type 1. The diagnosis is mainly suspected in the presence of symptoms and morphological features. Changes observed on conventional imaging are not typical and are usually similar to lesions observed in autoimmune pancreatitis type 2. AIP type 1 can also sometimes have a clinical or morphological presentation that mimics pancreatic cancer, especially pseudo-tumoral forms, associated with obstructive jaundice, weight loss and fatigue. Thus, the first challenge is to confirm the diagnosis of autoimmune pancreatitis and to exclude cancer. The AIP type must then be determined to decide on the most appropriate treatment.