Kidney and liver involvement in monoclonal light chain disorders.

Monoclonal light chains (LCs) are responsible for a wide spectrum of renal and hepatic diseases, that above all include amyloid light-chain (AL) amyloidosis and light chain deposition disease (LCDD). Amyloid deposits stain for Congo red on light microscopy and have fibrillar aspect on electron microscopy, whereas deposits in LCDD are positive using monotypic LCs on immunofluorescence and have a granular aspect on electron microscopy. Sometimes fibrillar and granular deposits are observed in the same organ or in different organs of the same patient. Kidney and liver involvement is a frequent finding, both in primary amyloidosis (AL amyloidosis) or in LCDD. Renal manifestations include proteinuria, nephrotic syndrome, and progressive renal failure. End-stage renal disease requiring dialysis is observed in about 20% of patients with AL amyloidosis and in 70% of patients with LCDD. The mean survival time is about 12 to 18 months in AL amyloidosis and 34 months in LCDD. The most important prognostic factor is severe cardiac involvement, which reduces the mean survival to only 6 months. Hepatic manifestations include hepatomegaly, portal hypertension, ascites, intrahepatic cholostatic jaundice, and hepatic insufficiency. The mean survival of patients with liver damage is 14 months, but it is reduced to 5 months in patients with cholostatic jaundice. Contemporary kidney and liver involvement is usually observed on histologic examination, less frequently as clinical manifestation. No specific treatment exists for AL amyloidosis and LCDD, and the prognosis remains severe. The aim of treatment is to suppress proliferation of the abnormal clone of plasma cells and remove tissue deposits. The regimens, including melphalan-prednisone (MP) or vincristine-doxorubicin-dexamethasone (VAD), are used both in AL amyloidosis or in LCDD with some effectiveness. New approaches, especially the use of 4'-iodo-4'deoxydoxorubicin, could achieve better results. Dialysis seems to not worsen the outcome in both diseases because survival of patients on dialysis is not different from that of patients not reaching uremia. Also, kidney and liver transplantation is effective, though amyloidosis or LCDD may occur in transplanted organs. The most interesting therapeutic approach is autologous-blood stem-cell transplantation, which may produce a complete remission of the plasma-cell dyscrasia and a substantial improvement of clinical manifestations related to LC deposits.