IgG4-associated sialadenitis

Purpose of review An enlarged salivary gland or lacrimal gland raises a wide differential diagnosis that includes both benign inflammatory conditions and malignant disorders. This review aims to address the numerous controversies that have arisen regarding inflammatory diseases of the salivary gland over the past two centuries and more specifically address the relevance of IgG4 in this setting. Recent findings A significant percentage of cases previously classified as Mikulicz disease, Kuttner tumor, and orbital pseudotumor (idiopathic orbital inflammation) show elevated numbers of IgG4-positive plasma cells, and some of these cases also show elevated levels of serum IgG4. These data support the evolving concept of IgG4-associated sialadenitis/dacroadenitis. The disease presents with enlargement of one of more salivary gland(s) and/or lacrimal gland(s). Histologically this disease is characterized by a dense polyclonal lymphoplasmacytic infiltrate, and is frequently associated with germinal centers, fibrosis and obliterative phlebitis. IgG4-bearing plasma cells are virtually always present, as is an elevated ratio of IgG4 to IgG containing plasma cells. Summary IgG4-related sialadenitis belongs to the IgG4-related systemic disease spectrum and shows a swift response to immunosuppression.