IgG4-Related Disease of the Head and Neck

IgG4-related disease (IgG4-RD) refers to a spectrum of rare clinical entities relating to lymphocytic infiltration of IgG4-secreting plasma cells, resulting in fibrosis and scarring. IgG4-RD can affect any organ system and frequently presents in multiple organ systems. Within the head and neck, the primary tissues affected include the lacrimal, salivary, and pituitary glands; paranasal sinuses; and orbits. Less common sites of involvement include cavernous sinuses and cervical lymph nodes. Clinical presentation and radiographic patterns are typically nonspecific. Therefore, diagnosis of IgG4-RD requires astute recognition of radiologic clues and correlation with tissue pathology. This article will focus on the ultrasound, CT, and MRI appearance of IgG4-RD of the head and neck and compare these imaging features with those seen in key differential diagnoses. Because delayed diagnosis can lead to irreversible long-term consequences and because IgG4-RD commonly shows swift response to corticosteroid and immunosuppressive therapy, rapid and accurate diagnosis is paramount.