IgG4-related systemic disease

Definition

A rare systemic autoimmune disease characterized by mass-forming lesions with a lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells and storiform fibrosis, often displaying obliterative phlebitis, and usually accompanied by elevated serum IgG4. Almost any organ may be affected, with pancreas, salivary gland, and orbit being the most common. Multi-organ involvement (synchronously or metachronously) is typical. Many patients show lymphadenopathy, most often involving the mediastinal, intra-abdominal, axillary, and cervical nodes. Symptoms are usually attributable to the mass effect of the lesions.