AbstractObjectives/Hypothesis:Immunoglobulin (Ig)G4‐related disease is a systemic syndrome, characterized by sclerosing lesions that mainly affect the exocrine tissue. Although some patients with IgG4‐related disease complain of nasal symptoms, there are few reports concerning the nasal manifestations of this disease. We investigated the clinical and pathological features of the nasal manifestations of IgG4‐related disease.Study Design:Retrospective review in a tertiary referral hospital.Methods:Twenty‐three consecutive patients with IgG4‐related disease, six allergic rhinitis (AR) patients, and eight healthy subjects (HS) were evaluated. Nasal symptoms, local findings of the nasal cavity, and laboratory data were examined. Mucosal tissues from the inferior turbinate were obtained from all subjects before treatment. The level of IgG4‐positive plasma cells and other infiltrating cells, and the number of nasal glands in the nasal subjects were compared among the three groups.Results:Ten (43.4%) of 23 cases had some nasal symptoms, such as nasal obstruction and nasal crusting. Thirteen cases (56.5%) had numerous IgG4‐positive plasma cell infiltration in the nasal mucosa. IgG4‐positive plasma cells, CD3, and CD4 were significantly higher in the IgG4‐related disease group than in the HS and AR groups, whereas the number of nasal glands in the IgG4‐related disease group was significantly lower than in the HS and AR groups.Conclusions:The inflammatory lesions associated with IgG4‐related disease exist on the nasal membrane. Thus, the nasal manifestations of IgG4‐related disease were thought to be different from AR.