LAUSR

Background Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated disease with single or multifocal mass lesions characterized by a fibrosclerotic inflammatory and lymphoplasmacytic infiltration that may affect unique or multiple organs. The pathophysiology of IgG4-RD is still not very clear. Rare cases have been documented in the maxillofacial region. Case Report The present study is to report a rare case of a middle-aged male patient with an increased mass in the lingual side of the left mandibular region over a year. The huge, movable, pedunculated, nodular lesion was adjacent to the gingiva, extending anteriorly to lateral incisor and posteriorly to first molar, and reaching the level of occlusal surface. First clinical impression was pyogenic granuloma. Further radiology, histopathology, and immunohistochemistry examinations revealed IgG4-RD. Excisional surgical treatment was performed and the outcome was good. Conclusions The precise diagnosis for the novel disease IgG4-RD is challenging. Knowing the potential for IgG4-RD to mimic other disorders and being aware of how to inspect and choose treatment strategies in patients by the current criteria will lead to better results.