Light Chain Fanconi Syndrome



Light Chain Fanconi Syndrome


Lynn D. Cornell, MD










Intracytoplasmic crystalline material that stained for monotypic light chain can be seen in the proximal tubules in this patient who had light chain Fanconi syndrome image.






Immunofluorescence staining reveals monotypic staining of intracytoplasmic crystals for kappa light chain. The stain for lambda was much weaker.


TERMINOLOGY


Abbreviations



  • Light chain Fanconi syndrome (LCFS)


Synonyms



  • Light chain proximal tubulopathy


  • Acute tubulopathy, light chain related



    • Related disorder with proximal tubular damage by toxic light chains


Definitions



  • Chronic tubulointerstitial nephropathy caused by intracytoplasmic crystalline inclusions composed of monoclonal light chains present in proximal tubular epithelial cells


ETIOLOGY/PATHOGENESIS


Monoclonal Immunoglobulin Light Chains



  • Produced by clonal proliferation of plasma cells



    • Most have multiple myeloma (may be smoldering) or monoclonal gammopathy of undetermined significance (MGUS)


    • Also associated with Waldenström macroglobulinemia and B-cell lymphomas


  • Normal light chains reabsorbed by proximal tubule, where they are degraded


  • In LCFS, abnormal light chain, usually kappa (VK1 subgroup), is resistant to enzymatic breakdown



    • Nephrotoxic light chains crystallize or precipitate within lysosomes in proximal tubules


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare (68 cases reported as of 2000)


Presentation



  • Fanconi syndrome (acquired)



    • Normoglycemic glycosuria


    • Aminoaciduria


    • Uricosuria


    • Hyperphosphaturia with hypophosphatemia


    • Type II renal tubular acidosis


  • Chronic renal failure, slowly progressive


  • Monoclonal gammopathy


  • Bence Jones proteinuria


  • Plasma cell dyscrasia or lymphoma


  • Adult-acquired Fanconi syndrome with monoclonal light chain raises suspicion of LCFS


Treatment



  • Treatment of underlying plasma cell dyscrasia or lymphoma


MICROSCOPIC PATHOLOGY


Histologic Features

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Light Chain Fanconi Syndrome
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