IgG4-related disease and other fibro-inflammatory conditions

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disease characterized by slow-growing and often pseudotumoural lesions that can be solitary or occur in multiple organs. The diagnosis of IgG4-RD requires the exclusion of a wide array of neoplastic, infectious and autoimmune disorders as well as of rare proliferative conditions such as histiocytoses and Castleman disease. The different subphenotypes of IgG4-RD (Mikulicz, head-and-neck limited, pancreato-hepato-biliary, retroperitoneal and/or aortic disease) differ in terms of patients’ demographic features, clinical manifestations and serum IgG4 levels. Treatment of IgG4-RD is based on the use of glucocorticoids, but B cell-depleting therapies (for example, rituximab or inebilizumab) are being incorporated into the standard therapeutic regimens. IgG4-RD is a chronic–relapsing disorder and therefore requires careful and long-term follow-up.