A 33-year-old man with overall renal function in the lower normal range had daily excretion in the urine of between 31 and 70 gm of protein composed entirely of free monoclonal K light chains. K light chains were also present in the serum. Serum protein electrophoresis and findings on bone marrow and lymph node biopsy were diagnostic of light chain disease. Amyloid was absent from renal tissue. General clinical improvement and almost total disappearance of protein from the urine followed treatment with phenylalanine mustard.
(Arch Intern Med 138:785-786, 1978)