IgG4-related inflammation of the orbit simulating malignant lymphoma.

Immunoglobulin (IgG) 4-related disease is characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. We report a case of IgG4-related inflammation of the orbit simulating extranodal marginal zone B-cell lymphoma (EMZL). A 72-year-old female complained of bilateral eyelid swelling for three years. A MRI scan demonstrated two kinds of lesions, tumor 1, presenting with a predominantly low density, and tumor 2, of relatively high density. Laboratory tests showed high serum IgG4 concentrations, measuring 991 mg/dl. Partial resection of each tumor was conducted in September 2011. Based on the clinicopathological findings, tumors 1 and 2 were diagnosed as IgG4-related inflammation and EMZL, respectively. The patient initially received oral prednisolone at 30 mg/per day, followed by irradiation with a total dosage of 30 Gy to both eyes. The bilateral tumors consequently diminished, and she is currently well with no recurrence or systemic involvement. In conclusion, EMZL can arise from massive IgG4-related orbital inflammation. Since IgG4-related inflammation can represent multiple nodular lesions, biopsies from multiple sites within the lesion are required to make a correct diagnosis in selected cases. Oral prednisolone combined with radiotherapy is an effective treatment for patients with IgG4-related ophthalmic disease simulating EMZL.