IgG4-related disease presenting with inflammatory pseudotumor of the buccal submucosa: A case report

Inflammatory pseudotumor is a rare clinical condition that may be associated with immunoglobulin G4-related disease. However, conclusive etiological links with immunoglobulin G4-related disease have not been identified in the few reported cases of oral inflammatory pseudotumors. We describe a case of an inflammatory pseudotumor of the buccal submucosa that was histopathologically confirmed to be a manifestation of immunoglobulin G4-related disease. The patient was an 83-year-old man who visited our department for the examination of swelling in the left buccal mucosa. The initial examination identified a painless, movable tumor with a long axis (approximately 40 mm) on the left buccal submucosa. Biopsy, magnetic resonance imaging, and computed tomographic findings did not clearly indicate malignancy, and the tumor was excised to facilitate a confirmative diagnosis. Histopathological examination revealed inflammatory cell infiltration of the adipose tissue as well as many lymphoid follicles. Immunohistochemistry predominantly revealed immunoglobulin G4-related disease-positive cells, thereby confirming the diagnosis of immunoglobulin G4-related disease. However, a postoperative blood test revealed normal immunoglobulin G4 levels, and steroid therapy was not initiated. The patient remains symptom- and recurrence-free at 18 months after surgery. (C) 2017 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.