Emerging treatment approaches for the systemic amyloidoses.

A 57-year-old man was diagnosed with AL amyloidosis after presenting with nephrotic syndrome. He had been well until 6 months earlier, when he noticed intermittent ankle swelling. He sought medical attention approximately 2 months later because of increased swelling of his legs and progressive fatigue. At that time, his urinary protein excretion was 7.4 g/day. Serum creatinine was 0.9 mg/dL and serum albumin 3.1 g/dL. A renal biopsy disclosed amorphous material in the mesangium that was birefringent under polarized light when stained with Congo red dye. Immunofluorescence was positive for lambda light chain in the glomerular capillary walls, mesangium, and tubulointerstitium. Electron microscopy revealed randomly dispersed fibrils with a diameter of 10 nm throughout the mesangium and interstitium. A monoclonal IgG lambda protein and a monoclonal free lambda light chain were evident by immunofixation electrophoresis (IFE) of the serum and urine, respectively. Bone marrow biopsy had 5% plasma