Abstract
IntroductionAcute renal failure in multiple myeloma is most frequently caused by cast nephropathy, when excess monoclonal free light chains co-precipitate with Tamm-Horsfall protein in the distal nephron, causing tubular obstruction. The natural history of cast nephropathy after diagnosis is unknown. This report provides supporting histological evidence that, as serum free light chain concentrations fall, intratubular casts may resolve within weeks.Case presentationWe report the case of a 61-year-old Caucasian woman who presented with multiple myeloma and dialysis-dependent acute renal failure, with serum kappa free light chain concentrations of 15,700 mg/litre (normal range 3.3 to 19.4 mg/litre). Renal biopsy demonstrated cast nephropathy with waxy casts in distal tubules and collecting ducts. There was an interstitial inflammatory cell infiltrate with diffuse fibrosis and tubular atrophy. Following rehydration, chemotherapy and free light chain removal using high cut-off haemodialysis, free light chain concentrations fell to less than 5% of the starting level (500 mg/litre). A repeat renal biopsy 6 weeks after the first showed resolution of cast nephropathy.ConclusionThese observations indicate that cast nephropathy can quickly resolve on rapid reduction of monoclonal serum free light chains. This has important implications for the development of treatment strategies aimed at improving renal recovery rates for patients in this setting.
Highlights
Acute renal failure in multiple myeloma is most frequently caused by cast nephropathy, when excess monoclonal free light chains co-precipitate with Tamm-Horsfall protein in the distal nephron, causing tubular obstruction
We report a case of a patient with cast nephropathy which resolved within 6 weeks after treatment with chemotherapy and high cut-off haemodialysis
A 40% reduction in serum free light chain (FLC) concentration to 8590 mg/litre was seen, but she remained in severe renal failure with an estimated glomerular filtration rate (eGFR) of
Summary
We believe that this report provides histological evidence that as serum FLC concentrations fall, intratubular casts can resolve within weeks. Diagnosis and treatment may facilitate reversal of acute renal failure. This observation has important implications for the development of combined haematological and renal treatment strategies aimed at improving renal recovery rates in this setting. Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal
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