Imaging of Common and Uncommon Manifestations of Immunoglobulin G4--Related Disease in the Head and Neck.

Immunoglobulin G4-related disease (IgG4-RD) is a multisystemic immune-mediated disease, encompassing several conditions previously thought to be unrelated, which can mimic malignant, infectious, and inflammatory disorders. Head and neck IgG4-RD most frequently affects the salivary glands and orbit; however, it can involve virtually any subsite. Diagnosis is challenging and relies on the clinical presentation, serum immunoglobulin G4 levels, and histopathology. Although imaging is nonspecific, growing knowledge of IgG4-RD allows characterization of imaging patterns and description of novel findings. This review focuses on cross-sectional imaging findings of extracranial IgG4-RD in the head and neck, presenting cases in frequent and unusual subsites, with some cases with few descriptions in the radiological literature, such as the pharynx and larynx, temporal bone, paranasal sinuses, and perivascular areas. Learning Objective: To describe the imaging findings of IgG4-RD in the head and neck to suggest the diagnosis and identify the involvement of common and uncommon subsites. [ABSTRACT FROM AUTHOR]