Rapid deterioration of renal function in a patient with multiple myeloma associated with amyloid and light chain depositions

Here we report a 75-year-old man with multiple myeloma who developed acute deterioration of renal function. Systemic AL amyloid deposition was found in the stomach, duodenum and brachial artery. A small amount of proteinuria without significant abnormal urinary sediments, increased excretion of urinary low-molecular-weight proteins and Bence Jones protein were observed. Significant renal Ga-67 uptake suggested acute tubulointerstitial lesions. Renal necropsy after sudden death 40 days after introduction of hemodialysis revealed mesangial expansion with glomerular basement membrane thickening, tubular basement membrane thickening with or without tubular atrophy and massive tubulointerstitial fibrosis. Slight amyloid depositions in the mesangium and vessels, and massive granular electron-dense deposits and deposition of monoclonal light chain λ in renal basement membranes and vessels were found, indicating the rare condition of co-existence of amyloidosis and light chain deposition disease (LCDD). The rapid progression of renal failure may have been caused by massive deposition of monoclonal light chains in our patient.