IgG4-related disorders (IgG4-RD) are a new entity of multi-organ disorders that share common fibro-inflammatory histopathologic characteristics and elevated IgG4 levels in serum and tissue. Autoimmune pancreatitis and Mikulicz syndrome are major entities, however many syndromes are part of IgG4-RD including eosinophilic angiocentric fibrosis, fibrosing mediastinitis, hypertrophic pachymeningiti...