Nephropathology
   
Case 114
Diagnosis
 
     
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Diagnosis: Light chain (kappa) proximal tubulopathy

The most common paraprotein-related diseases of the kidney are amyloidosis, light chain deposition disease and light chain cast nephropathy. Less common forms of paraproteinemic disease in multiple myeloma include cryoglobulinemic glomerulonephritis and light chain proximal tubulopathy. In this patient a bone marrow biopsy confirmed the diagnosis of multiple myeloma.

Light chain proximal tubulopathy is a form of proximal tubule injury secondary to increased filtration of pathogenic light chains. The classic and most widely recognized form of this disease has kappa-restricted intracytoplasmic crystals on renal biopsy and the clinical manifestation of a Fanconi’s syndrome. In recent years, the pathologic spectrum has been expanded to include cases with fibrillary cytoplasmic inclusions and those showing light chain restriction within the lysosomes without inclusions (Christopher P, et al. Amyloid proximal tubulopathy: a novel form of light chain proximal tubulopathy. Clinical Kidney Journal 2012;5:130-2. [Abstract]).

Proximal tubular damage by light chains results in acute tubular necrosis. The early changes include vacuolization of the tubular cells followed by apical blebbing with loss of surface microvillous borders, desquamation, and fragmentation. Monoclonal light chains may be detected in the cytoplasm of the tubular cell corresponding to the localization of the light chain in lysosomes (Heptinstall's Pathology of the Kidney, 6th ed. p. 864).

See the chapter Amyloidosis, Multiple Myeloma, and others of our tutorial.

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References

  • Herlitz LC, D'Agati VD, Markowitz GS. Crystalline nephropathies. Arch Pathol Lab Med. 2012;136(7):713-20. [PubMed link] [Full text link]
  • Christopher P. Larsen, G. Scott Borrelli, and Patrick D. Walker. Amyloid proximal tubulopathy: a novel form of light chain proximal tubulopathy. Clinical Kidney Journal 2012;5:130-2. [Abstract]
  • Sanders PW. Mechanisms of Light Chain Injury along the Tubular Nephron. J Am Soc Nephrol. 2012 Sep 20. [Epub ahead of print] [PubMed link]
  • Herlitz LC, Roglieri J, Resta R, Bhagat G, Markowitz GS. Light chain proximal tubulopathy. Kidney Int. 2009;76(7):792-7. [PubMed link]

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