Immunoglobulin G4-related disease in the skull base mimicking nasopharyngeal carcinoma.

Immunoglobulin G4-related disease (IgG4-RD) is a rare clinical condition. Although it has been described in the head and neck region, skull base involvement is exceedingly uncommon. We present a clinical report of a patient with IgG4-RD of the skull base that mimicked nasopharyngeal cancer. This case highlights challenges in the clinical diagnosis of this rare condition. The diagnosis could be made only on histopathologic evaluation, which showed dense fibrosis with lymphoplasmacytic infiltration by IgG4-positive plasma cells. Serum IgG4 level was also elevated. Once IgG4-RD was confirmed, treatment with glucocorticoid yielded a good clinical outcome.