Orbital necrobiotic xanthogranuloma associated with systemic IgG4 disease

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.

Immunohistochemistry for total IgG and IgG4 was performed in 18 cases of orbital inflammation, including chronic dacryoadenitis (n=10), necrobiotic xanthogranuloma (n=2), xanthogranuloma (n=1), idiopathic orbital inflammation/pseudotumor (n=4), and fungal infection (n=1).

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).

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.