Renal amyloidosis complicated by light chain deposition nephropathy: a case report.

Light chain amyloidosis (AL) and light chain deposition disease (LCDD) are systemic diseases caused by an abnormal production of monoclonal immunoglobulin light chains and their deposition in systemic tissue. We herein present a rare case of renal amyloidosis complicated with light chain deposition nephropathy. The patient presented with nephrotic syndrome and an increased serum creatinine. Laboratory studies showed the serum k light chain was decreased and the urine free λ light chain was positive. On a lighted microscopy examination of the renal cortical tissue, λ and κ light chain protein deposits were in the glomerular and renal tubular basement membranes and Congo red staining was positive. It was determined using electron microscopy that amyloid fibrils and continuous electron-dense granules were deposited in the glomerular basement membrane. Due to differences in the protein polymerization mechanisms, it is almost impossible for AL and LCDD to coexist. This rare case can help provide ideas for clinical diagnosis and for exploring new therapeutic targets.