Thoracoabdominal manifestations of immunoglobulin G4-related disease.

Immunoglobulin G4-related disease (IgG4-RD) comprises a group of immune-mediated diseases that, until recently, were considered separate entities. These entities have a similar clinical presentation, serological findings, and pathogenesis, so they are currently considered a single multisystemic disease. The common characteristic is the infiltration of involved tissues by plasma cells and lymphocytes that are positive for IgG4. Three major criteria have been proposed for the diagnosis of IgG4-RD: clinical, laboratory, and histological. The pancreas is the organ that is most affected by IgG4-RD, which can simulate a tumor. In this respect, a series of signs could help us suspect that the pancreatic findings do not reflect a tumor (halo sign, duct-penetrating sign, absence of vascular invasion, etc.). The differential diagnosis is important to avoid unnecessary surgical interventions.