Clinical, biochemical, and pathological features in a patient with plasma cell dyscrasia and Fanconi syndrome

Multiple myeloma is associated with a wide array of renal diseases that inc lude myeloma cast nephropathy, monoclonal immunoglobulin deposition disease , amyloidosis, cyoglobulinemia, tubular dysfunction, pyelonephritis, nephro calcinosis, urate nephropathy, and infiltration by atypical plasma cells (o r myeloma cells). Filtered immunoglobulin light chains may affect both the distal and, more frequently, the proximal tubule. Tubular abnormalities in patients with plasma cell dyscrasia may be more frequent than previously th ought. A patient with a plasma cell dyscrasia is described, who presented w ith biochemical features consistent with Fanconi syndrome. Immunoelectron m icroscopy performed on the renal biopsy confirmed the presence of kappa lig ht chain immunoglobulin in intracytoplasmic crystals in proximal tubular ep ithelial cells. This report is one of a few demonstrating the presence of l ight-chain immunoglobulin in intratubular crystals in a human renal biopsy obtained from a patient with a plasma cell dyscrasia and Fanconi syndrome.