Progressive Renal Failure Due to Recurrent Attacks of Polyclonal Light-Chain Cast Nephropathy Induced by Recurrent Chest Infections Ablated by Rituximab

Background: Cast nephropathy is reported only with monoclonal light-chain gammopathy. The case: A 38-year-old white male was referred for management of progressive renal failure (serum creatinine at 294 µmol/L). He had cigarette-induced bronchiectasis and 2 attacks of partially resolving acute renal injury associated with chest bacterial infections 2 years and 1 month ago. Ultrasonography revealed 9 cm kidneys with thin and echogenic cortex. Autoimmune diseases and lymphoproliferative disorders/myeloma were excluded by laboratory and radiological tests as well as bone marrow biopsy. Kidney biopsy showed focal segmental glomerulosclerosis with distal tubules studied with PAS-ive casts surrounded by inflammatory cells, and moderate interstitial fibrosis. Immunohistochemical studies did not show glomerular immune deposits, yet antibody to both light chain Kappa and Lambda were detected in those casts and the intratubular epithelial droplets. Hence, after control of his infections and cigarette cessation, he was treated with yearly Rituximab infusions. Despite having 2 subsequent attacks of chest infections, over 2 years of follow-up, he did not experience new renal injury or deterioration. Conclusion: In predisposed individuals, recurrent infection can induce polyclonal light-chain cast nephropathy which is amenable to Rituximab.