Raised Numbers of IgG4-Positive Plasma Cells Are a Common Histopathological Finding in Orbital Xanthogranulomatous Disease

Purpose: To determine the relation of orbital xanthogranuloma with IgG4-related disease. Methods: Retrospective consecutive case series over a period of 25 years. We searched our charts for histologically confirmed orbital xanthogranuloma. Patient files were reviewed for clinical and follow up data including presence or absence of systemic non-ophthalmic manifestations of IgG4 related disease. Slides were re-examined and histopathological classification was re-assessed. Sixteen cases of orbital xanthogranuloma were evaluated. Immunohistochemical stains for IgG and IgG4 were performed. Positive immunohistochemical staining required increased IgG4-positive plasma cells in the involved tissues scored as > 50 per high-power field, with IgG4/IgG ratio > 0.40. Results: According to the criteria described above 8/16 (50%) cases showed increased numbers of IgG4-positive plasma cells in the specimens. Two of these patients may have had signs of systemic disease Conclusion: Raised numbers of IgG4-positive plasma cells are a common finding in histopathological specimens of xanthogranulomatous disease of the orbit and are often not indicative for IgG4 related systemic disease.