Light chain nephropathy: histological and clinical aspects in 15 cases.

Fifteen patients aged 31-74 years (five male, ten female) on renal biopsy showed intense linear deposits of light chains along tubular basement membranes (TBM) by immunofluorescence, and/or granular dense deposits on electronmicroscopy. Multiple myeloma was diagnosed in ten patients. The onset of myeloma and nephropathy was simultaneous in six patients; nephropathy preceded or followed the diagnosis of myeloma in three and one patients respectively. The mode of onset of nephropathy was acute or rapidly progressive renal failure in five cases, chronic renal failure in seven, and heavy proteinuria in three. Only two patients had normal renal function at biopsy. Serum monoclonal component was kappa in five patients, IgG kappa in three, IgD kappa in one, IgG lambda in one, IgA lambda in one, absent in three, and not detected in one. On light microscopy eight cases had nodular glomerulosclerosis, three cast nephropathy and 14 TBM thickening. Immunofluorescence for monoclonal light chain(s) was positive in 11 of 13 cases. Electron microscopy showed finely granular deposits in the inner side of glomerular basement membranes (GBM) and the outer side of TBM in 11 of 11 tested cases. The evolution was towards chronic renal failure in 12 patients (six of whom required dialysis), death in two, unknown in one. Four patients died after a period of dialysis, from infections or cardiovascular complications.