Solitary Iris Plasmacytoma With Anterior Chamber Crystalline Deposits

Purpose: To report a case of solitary iris plasmacytoma successfully treated with ruthenium plaque radiotherapy. Methods: A 44-year-old white woman presented with pain in the right eye and raised intraocular pressure. Her medical history included breast cancer treated 11 years earlier with lumpectomy, lymph node clearance, chemotherapy, and radiotherapy. On examination, the right iris had a tan-colored mass with crystalline deposits visible on the mass surface and on the corneal endothelium. The fundus and left eye were normal. An anterior segment ultrasound scan showed a mass with mixed internal echogenicity and internal blood flow. Results: An iris biopsy showed an infiltrate of plasma cells. Immunohistochemistry for kappa and lambda light chains demonstrated lambda light chain restriction. Systemic hematologic investigations including complete blood count, serum paraproteins, bone marrow biopsy, and full-body magnetic resonance image were normal. The monoclonal plasma cell infiltrate was consistent with a solitary iris plasmacytoma. The mass was treated with ruthenium plaque radiotherapy. After 4 years of follow-up, the mass remained regressed, and no systemic myeloma has developed. Conclusions: Iris plasmacytoma is rare and should prompt systemic evaluation to rule out multiple myeloma. Solitary iris plasmacytoma can be successfully treated with plaque radiotherapy.