IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a recently described fibroinflammatory disease, of autoimmune origin, characterized by tumefactive masses that can be found in virtually any organ, hypergammaglobulinemia and increased IgG4 levels in more than 50% of patients. Histologic analysis shows dense tissue infiltration of lymphocytes and IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis. Clinical presentation is extremely variable, and four disease phenotypes with different patterns of organ involvement have been identified. The diagnosis is based on the combination of clinical, radiologic, histopathologic, and serologic findings. Glucocorticoids are the first-line treatment for induction of remission in patients with active disease. Conventional DMARDs and/or biologic agents are frequently added in relapsing or refractory forms. Some patients show a progressive course due to fibrotic changes in affected tissues. Increased risk of malignancy involving many organs and tissues has been reported.