IgG4-related Sclerosing Disease An Emerging Entity Frequently Misdiagnosed

IgG4-related sclerosing disease, a multiorgan system disease that has been identified in the last 10 years, is a fibroinflammatory condition with a marked propensity to manifest itself as mass forming lesions characterized by three main histological features (sclerosis, obliterative phlebitis and lymphoplasmacytic infiltrate) and by the presence of abundant IgG4+ plasma cells, frequent elevation of serum IgG4 and a dramatic initial response to steroid therapy. The aim of this mini-review is to increase the capacity to identify the characteristic features of IgG4-related sclerosing disease in specific organs and in two newly proposed entities (urethral caruncle and para-testicular fibrous pseudotumor) using biopsy specimens and methods of counting IgG4. In addition we examine the relationship between IgG4-related sclerosing disease and malignancy. In fact, an increased ability to recognize the characteristic features of IgG4-related sclerosing disease would play an extremely important role in avoiding unnecessary surgery in favor of initiating corticosteroid therapy.