Orbital and muscle involvement in multiple myeloma.

CASE REPORT: We report 2 cases of orbital plasmacytoma in patients with known multiple myeloma. Orbital spread with secondary maxillary sinus involvement is reported in the first case. Case 2 is the first report of immunoglobulin A kappa light chain multiple myeloma involving orbital recti muscles. Computed axial tomography and magnetic resonance imaging aided the diagnosis, confirmed with histopathologic studies. COMMENTS: Extraskeletal spread is rare and orbital involvement is exceedingly uncommon. From a review of the literature since 1972, we conclude that the immunoglobulin G type of multiple myeloma, whether lambda or kappa light chain, may be a risk factor for orbital involvement.