Perplexing Lesions of the Sinonasal Cavity and Skull Base IgG4-related and Similar Inflammatory Diseases

ObjectiveIgG4-related disease (IgG4RD) causing sinonasal and skull base pathology is uncommonly described. We present a series of suspected IgG4RD patients, with a pertinent review of the literature to highlight diagnostic challenges.Study DesignCase series.SettingAcademic tertiary care center.Subjects and MethodsCase series of patients with IgG4RD or suspected IgG4RD involving the sinonasal cavity and skull base.ResultsWe present 4 patients with atypical sinonasal and/or skull base disease who were noted to have IgG4-positive plasma cell infiltration on immunohistochemistry of biopsy specimens. IgG4RD, a recently described entity affecting multiple organs, is characterized by lymphoplasmacytic infiltration and often elevated serum IgG4. IgG4RD can masquerade as malignancy or infection but responds to glucocorticosteroid and immunosuppressant therapy. IgG4RD has been infrequently reported presenting as sinonasal or skull base lesions, and definitive diagnostic criteria for these regions are not establishe...