Paraproteinemic corneal deposits in plasma cell myeloma

We treated two patients who had IgG-kappa-light chain monoclonal gammopathy with partially crystalline and partially amorphic corneal deposits. Impairment of vision made keratoplasty necessary for each patient. Histologic examination of the corneal specimens showed deposits that stained positively for Masson's trichrome in all corneal cells. Immunohistochemical tests identified these deposits as IgG-kappa-light chain immunoglobulin fragments. Electron microscopy showed intracellular, rhomboid-shaped deposits enveloped by a membrane. The same deposits appeared in the conjunctival epithelium, within subconjunctival fibrocytes, and in the plasma cells of the bone marrow. Immunoelectrophoresis showed IgG-kappa-light chain fragments in the blood serum, the lacrimal film, and the aqueous humor. This suggests that the intracellular immunoglobulin fragments may have entered the corneal and conjunctival epithelium by way of the lacrimal film, the keratocytes by way of the corneo-scleral limbus vasculature, and the endothelial cells from the aqueous humor.