[IgG4-related disease--a common denominator of many conditions previously regarded as being confined to a single organ].

IgG4-related disease is a newly recognized systemic condition characterized by high serum IgG4 levels and an inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosis and obliterative phlebitis. It predominantly affects middle-aged or elderly males and was first described as autoimmune pancreatitis. The disease may also involve the hepatobiliary tract, salivary glands, orbit, lymph nodes, and the lungs, aorta, retroperitoneum, skin, nervous system, kidneys and thyroid gland. It may mimic infections, malignancies, and other immune-mediated conditions. Histopathology and immunohistochemistry form the basis of the diagnosis. Glucocorticoids are usually effective but relapses occur commonly.