IgG4-related Disease in Thymus. A Very Rare Case of Chronic Fibrosis Mimicking Sarcoidosis

IgG4-related disease (IgG4-RD) is a multi-organ immune-mediated chronic fibroinflammatory condition, with unclear certain etiology. It is morphologically characterized by storiform fibrosis, dense IgG4-positive lymphoplasmacytic infiltrate, and obliterative phlebitis. It was recognized as a systemic condition as recently as 2003. IgG4-RD has been described in virtually every organ, forming sclerosing masses, and often mimicking tumors....