Imaging features of immunoglobulin G4-related disease.

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that was first recognised as a systemic disease in 2003, when patients with autoimmune pancreatitis were found to have extrapancreatic manifestations. Since 2003, IgG4-RD has been described in a diverse range of other organs including the biliary tree, orbits, lacrimal glands, salivary glands, lungs, kidneys, aorta, retroperitoneum, lymph nodes, pachymeninges, prostate and pituitary gland. The disease frequently occurs in the absence of pancreatic involvement. The imaging manifestations of IgG4-RD are broad and variable depending on the organ involved. The majority of individual organ appearances are non-specific and differentiation between IgG4-RD and potentially more serious conditions is not usually possible based on radiological findings in one organ alone. However, if there are simultaneous findings typical of IgG4-RD in multiple organs then this is a key diagnostic clue and IgG4-RD should be considered as one of the main differentials. This review article examines the spectrum of imaging appearances of IgG4-RD. Increased awareness of the spectrum of radiological appearances of IgG4-RD throughout the body and subsequent consideration of the condition may potentially avoid invasive treatment and lead to more prompt corticosteroid therapy.