IgG4-related disease in the head and neck region: report of two cases and review of the literature.

IgG4-related disease (IgG4-RD) is a rare immune-mediated condition characterized by extensive tissue fibrosis and infiltration by immunoglobulin G4 positive plasma cells in a single organ or systemic appearance. Two cases are presented including an unusual case of a 30-year-old man with IgG4-RD appearing simultaneously in the cervical lymph nodes, ethmoid, maxillary sinuses, and upper gingiva, with spontaneous loss of teeth. According to the literature, this is the first case with loss of teeth occurring in the course of the disease. The second case is a 46-year-old man suffering from IgG4-related chronic sclerosing sialadenitis of the right submandibular gland.