A case of IgG4-related disease with initial symptoms in the labial salivary gland

Abstract Immunoglobulin G4-related disease (IgG4-RD) is a chronic disease characterized by elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells into the lesions in the tissue. In the mandibulofacial region, the initial symptoms are often observed in the submandibular glands, but rarely in the labial salivary gland (LSG), which are minor salivary glands. Here, we report our experience with a case of IgG4-RD, in which the initial symptoms were observed in a LSG. The patient was a 71-year-old woman who visited our department for examination of a swelling in her lower lip. At the first examination, a painless, movable tumor with a long axis of approximately 20 mm was observed on the left lower lip. Ultrasonography, MRI, and CT findings indicated IgG4-RD. In a blood test, the IgG4 level was 297.0 mg/dL. A biopsy revealed lymphocyte and plasma cell infiltration accompanied by secondary folliculogenesis and acinar atrophy in the LSG tissue. Immunohistochemical staining showed many IgG4-positive cells. IgG4-RD was diagnosed based on the above findings. Steroid therapy was initiated after reaching a definitive diagnosis, after which the course progressed with no recurrence of symptoms.