Multiple myeloma involving the orbit.

Multiple myeloma is a plasma cell malignancy often associated with destructive skeletal lesions. Orbital involvement in multiple myeloma is rare. Risk factors for orbital involvement have not been established, although risk may vary with immunoglobulin subtype. Early detection of orbital plasmacytoma may affect treatment and clinical course. A case is reported of multiple myeloma without elevated serum immunoglobulins that involves the orbit, and the implications of early detection are discussed. The patient was first examined by an ophthalmologist 13 months after multiple myeloma was diagnosed and 5 months after the external appearance of an orbital tumor. Urine protein electrophoresis demonstrated kappa light chains. Hypergammaglobulinemia was not detected. Plain-film roentgenography showed orbital involvement at the time of initial diagnosis. An impressive clinical response to external beam radiation therapy was seen. Attention to immunoprotein characteristics in multiple myeloma may help to identify risk factors for orbital involvement. Early detection may permit safer and equally effective treatment. All patients with multiple myeloma should undergo thorough ophthalmic examination at the time of initial diagnosis.