IgG4-related disease and the current status of diagnostic approaches.

IgG4-related disease is a newly recognized systemic disease characterized by involving a wide range of organs. It includes the pancreas, biliary tree, salivary glands, periorbital tissues, upper aerodigestive tract, retroperitoneum, mediastinum, aorta, soft tissue, skin, central nervous system, breast, kidneys, prostate, lungs and lymph nodes. The elevated serum titer of immunoglobulin G4 (IgG4), which is the least common (3 % to 6 %) of the 4 subclasses of IgG, is a special marker for IgG4-related disease. However, its entity is still unknown. This article reviewed the literature to learn the IgG4-related diseases and their current status of diagnostic approaches.