Autoimmune pancreatitis was found to be associated with highy elevated serum immunoglubin G4 (IgG4) levels in 2001. Since then, the disease was recognized as a systemic condition with frequent occurrence of extrapancreatic manifestations. In the following years, IgG4 - Related Disease (IgG4-RD), a fibroinflammatory disorder characterized by tumefactive lesions, dense lymphoplasmacytic infiltrates with IgG4-positive plasma cells, storiform fibrosis and elevated IgG4 serum levels, was defined. Manifestations have been described for nearly every organ system now, and diseases, that have been confined to single organs for a long time, have been charactarized as part of IgG4-RD. The pathophysiology and origin of this rare disease is largely unknown.
IgG4RD can affect single or multiple organs, resulting in either diffuse or localized lesions. Clinical presentation is usually subacutely and most patients do not have consitutional symptoms or systemic signs of inflammation. However, life- threatening events such as aortic rupture or liver failure do occur and therefore timely diagnosis and therapy is important. Many, but not all, patients present with strongly elevated serum IgG4 levels. In most organs, a typical histological picture as described above can be found.
Currently, there is a lack of data from randomized, controlled trials regarding the treatment of IgG4-RD. Watchful waiting might be adequate for asymptomatic organ involvement. The mainstay of therapy is glucocorticoids, but relapses are common upon GC tapering. Azathioprine, methotrexate and other immunosuppressive drugs are currently used for relapsing disease. Refractory disease has been successfully treated with rituximab. Immunosuppression seems to be more effective during inflammatory stages of the disease than in patients with established fibrosis.
Disclosure of Interest J. Zwerina Grant/Research support from: Roche, Consultant for: Roche, Conflict with: Roche