[IgG4-related disease].

IgG4-related disease is an emerging pathological condition characterized by one or several fibrosing and inflammatory organ involvements. Histological findings are typical and associate storiform fibrosis with polyclonal lymphocytic and plasma-cell infiltrate, with predominant IgG4-expressing plasma cells. Sclerosing lymphoplasmocytic pancreatitis, or type 1 auto-immune pancreatitis, and other organ involvements have been reported: sclerosing cholangitis, sialadenitis, dacryoadenitis, retroperitoneal fibrosis, aortitis, interstitial nephritis, polyadenopathy and inflammatory pseudo-tumors. Serum IgG4 level is elevated in most of patients, but the histological documentation remain necessary for the diagnosis. Dramatic response to steroids is usual but relapses are frequent.