Five Cases of IgG4-related Disease with Nasal Mucosa and Sinus Involvement.

We herein report five patients with nasal mucosa and sinus involvement who were diagnosed with immunoglobulin G4-related disease (IgG4-RD). In all cases, the lacrimal, parotid, and submandibular glands were swollen; biopsies of these glands were risky, so the labium and nasal mucosa were instead targeted. All patients tested positive through these biopsies, suggesting alternative sites for confirming IgG4-RD. These five patients had first been diagnosed and unsuccessfully treated for allergic rhinitis or chronic sinusitis. After the IgG4-RD diagnosis, they were administered corticosteroid therapy, which drastically improved the nasal mucosa and sinus involvement. When refractory allergic rhinitis or sinusitis is detected, IgG4-RD should be considered.