To review the definition and diagnosis of IgG4-Related Disease (IgG4-RD). To describe computed tomography (CT) and magnetic resonance (MR) typical and atypical imaging findings of IgG4-RD in different sites of head and neck.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic condition characterized by tumefactive lesions, an extensive lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, fibrosis of unknown etiology and elevated serum IgG4 concentrations that affect a wide variety of organs [1]. This condition was not recognized as a systemic disease until 2003, when Kamisawa [2] reported multiple extrapancreatic lesions in patients with autoimmune pancreatitis and the histopathology identified with affected organs was identical to that found in the pancreas. They proposed the existence of an entity that was...

A - Diagnosis Although IgG4-RD has been recognized as a new clinical entity worldwide, uniform international criteria for diagnosing IgG4-RD have not yet been established. The presence of many clinical mimics of IgG4-RD may result in over-diagnosis of this disease. Histopathological examination of these lesions reveals both inflammatory elements in the form of a lymphoplasmacytic infiltrate, often accompanied by a mild tissue eosinophilia, and a fibrotic component characterized by “storiform” fibrosis. Immunohistochemistry studies reveal a preponderance of IgG4-positive plasma cells [6]. Guidelines for diagnosis of...

IgG4-RD is an autoimmune fibrosing disease whose pathology is still in discussion. As knowledge has increased about the disease, there is increased reports of new organ involvement previously not described. MR imaging is the method of choice for evaluating this entity. Findings such as low signal intensity in T2 wheighted images, an enhancing infiltrative tissue, multysistemicinvolvement and predilection for certain sites of involvement (pancreas, salivary glands and retroperitoneum) helps the radiologist to suggest this treatabledisease.

Hugo Luis de Vasconcelos Chambi Tames, MD Fellow in head and neck imaging - Hospital das Clínicas da Faculdade de Medicina da USP - University of São Paulo - São Paulo/Brazil. [email protected]

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