Light-chain nephropathy in patient with renal carcinoma.

Paraneoplastic syndromes are often associated with renal parenchymal tumours. This report describes a case of renal-cell carcinoma with kappa-chain nephropathy. The patient, a 60-year-old man, had renal tubular dysfunction, shown by low serum concentrations of urate and phosphate. Kappa-chains were found in both serum and urine, but no lambda-chains were found. Investigations showed a clear-cell carcinoma, and the patient underwent a radical nephrectomy. Two years after operation serum phosphate and urate concentrations had returned to normal, and kappa-chains were undetectable in serum or urine. The absence of lambda-chains indicates that the light-chain proteinuria was due to overproduction of the M component, and the disappearance of kappa-chains after the operation suggests a causal relation between the renal tumour and the overproduction of the M component.