Detection of Myeloma Cells in the Urine Sediment

The urine sediments of 18 patients with multiple myeloma were stained with tetrachrome stain and examined by light microscopy. Eleven of the eighteen sediments contained cells with the morphologic characteristics of plasma cells. When stained with fluoroscein conjugated rabbit immune globulin prepared against κ and λ light chains, eight of these sediments contained fluorescent staining plasma cells. In each case the cells stained with the antibody to the light chain of the patient’s myeloma protein and not with the other light-chain antibody. Examinations of sediment from patients with other types of renal disease and normal subjects did not reveal the presence of fluorescent staining cells. In the urine of two myeloma patients, cells were identified as plasma cells by electron microscopy. No correlation was found between the presence of plasma cells and the patient’s monoclonal protein, light-chain type, or the presence or degree of renal disease. The finding of myeloma cells in the urine presumably indicates an extramedullary extension of the disease, and their presence may contribute to the renal impairment commonly found in myeloma patients.