Orbital necrobiotic xanthogranuloma associated with systemic IgG4 disease

Purpose: The authors describe 2 cases of orbital xanthogranulomatous disease associated with an increase in IgG4-positive plasma cells, and also examine IgG4 in other types of orbital inflammation. Methods: Immunohistochemistry for total IgG and IgG4 was performed in 18 cases of orbital inflammation, including chronic dacryoadenitis (n10), necrobiotic xanthogranuloma (n2), xanthogranuloma (n1), idiopathic orbital inflammation/pseudotumor (n4), and fungal infection (n1). Results: One patient presenting with necrobiotic xanthogranuloma had signs of systemic IgG4 disease. His orbital lesion showed an elevated number of IgG4 positive plasma cells (55%). An orbital xanthogranulomatous lesion in a second patient lacking systemic symptoms also contained a high percentage of IgG4-positive plasma cells (80%). Only 1 case of chronic dacryoadenitis contained prominent IgG4-positive plasma cells (mean 17/hpf). Conclusions: IgG4-positive plasma cells are relatively rare in nonsclerosing orbital inflammatory lesions. However, systemic disease IgG4 can be associated with necrobiotic xanthogranuloma of the orbit.