Immunoglobulin G4 related sclerosing disease mimicking a lytic lesion of the mandible: a case report and review of literature.

Background: Immunoglobulin G4 related disease (IgG4-RD) is an immune-mediated, multifocal, fibroinflammatory disease with varied clinical manifestations. The involvement of head and neck region is infrequent. The objective was to report a case of localized IgG4-RD of mandible that clinically mimicked a lytic lesion.

Case presentation: A 22 year old female presented with restricted mouth opening and swelling over right ramus and angle region of mandible. Radiographic imaging showed an ill-defined radiolucent lytic lesion infiltrating adjacent muscles. An incisional biopsy was performed and histopathological picture was suggestive of benign spindle cell neoplasm. Immunohistochemistry was suggestive of IgG4-RD involving mandible adjoining soft tissues. Elevated serum IgG4 levels were noted. Oral steroid therapy was initiated and tapered without maintenance dose. The patient progressed without any sequelae. Imaging 2 years after completion of treatment showed complete resolution of the radiolucent lesion.

Conclusion: The precise diagnosis of this lesion is challenging and depends on many different factors. A non-specific localized lesion should be investigated as a systemic condition. Early diagnosis and prompt initiation of steroid therapy should be favored. Continued follow up is critical due to the indolent nature of this disease. The future of management of this disease is the development of specific diagnostic criteria and targeted therapy of head & neck lesions.