Immunoglobulin G4-related diseases (IgG4-RD) are a group of diseases characterized by high serum levels of immunoglobulin G4 (IgG4), increased lymphocyte and plasma cell with IgG4 positivity in the parenchyma of some organs, and storiform fibrosis. The most frequently affected organ is the pancreas. This is an autoimmune form of pancreatitis, which can be divided into two types: Type 1, which is significantly more common than Type 2, is high in IgG4 in the pancreatic parenchyma and shows a fundamental difference in the noted presence of extrapancreatic disorders. In general, chronic inflammation is a risk factor in the development of carcinomas. Chronic pancreatitis is an accepted risk factor for the development of pancreatic cancer. The question is whether this also applies to autoimmune pancreatitis (AIP), which has some mediators of inflammation in common with sporadic pancreatitis, and what role the presence of IgG4 plays. The vast majority of the work on this topic consists of case reports, yet, even based on our own experience, we would like to say that there is a relationship between the autoimmune form of pancreatitis and pancreatic cancer, which usually occurs in the first two years after diagnosis of AIP. Also significant is the fact that the group of people with AIP, who is a clinical manifestation of IgG4-RD, was found to have an even higher incidence of extrapancreatic cancer than in the pancreas itself. Differentiating AIP from pancreatic cancer can sometimes be problematic since these diseases can both present as focal pancreatic lesions. IgG4 has been considered useful for AIP diagnosis, however, IgG4 levels can be slightly elevated, as in the case with pancreatic adenocarcinoma. IgG4 levels of over twice the upper limit are rare among patients with pancreatic adenocarcinoma. However, cases of simultaneous presentation of pancreatic cancer and AIP have been documented and should not be neglected. AIP is a condition where regular followup is mandatory, including from the perspective of possible cancerogenesis.
Keywords: Carcinogenesis; autoimmune pancreatitis; cancerogenesis; chronic inflammation; chronic pancreatitis; immunoglobulin G4.; pancreatic adenocarcinoma.