Membranoproliferative glomerulonephritis: the role for laser microdissection and mass spectrometry.

Abstract

Monoclonal gammopathy is increasingly recognized as a common cause of membranoproliferative glomerulonephritis (MPGN); however, establishing this diagnosis can be challenging. We report the case of a 58-year-old asymptomatic woman who presented with proteinuria with protein excretion of 5,000mg/d, microscopic hematuria, and normal kidney function. Kidney biopsy was consistent with MPGN pattern of injury. Immunofluorescence studies were positive for nonspecific segmental immunoglobulin M (IgM) and C3 staining. Electron microscopy showed subendothelial, subepithelial, and mesangial electron-dense deposits. The workup excluded an infectious or autoimmune disease, but IgG κ monoclonal protein was detected in serum at a concentration of 0.4mg/dL. Because there was a mismatch between the serum monoclonal protein (IgG κ) and immunofluorescence staining pattern (nonspecific IgM, no light chain restriction), laser microdissection and mass spectrometry were performed on the kidney biopsy tissue. This identified the deposits as monoclonal IgG κ, thereby leading to the diagnosis of monoclonal gammopathy-associated MPGN. Our case emphasizes the importance of searching for an underlying cause of MPGN, reviews the technique of laser microdissection-mass spectrometry, and highlights its application as a pathology tool for the evaluation of monoclonal gammopathy-related glomerulonephritis.

• Authors: Deepika Jain, Jamie A Green, Sheldon Bastacky, Jason D Theis, Sanjeev Sethi
• Journal: American journal of kidney diseases : the official journal of the National Kidney Foundation (Am J Kidney Dis) Vol. 63 Issue 2 Pg. 324-8 (Feb 2014) ISSN: 1523-6838 [Electronic] United States
• PMID: 24145022 (Publication Type: Case Reports, Journal Article)
• Copyright: Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Chemical References

• Immunoglobulin kappa-Chains

Topics

• Female
• Glomerulonephritis, Membranoproliferative (diagnosis, metabolism)
• Humans
• Immunoglobulin kappa-Chains (physiology)
• Mass Spectrometry (methods)
• Microdissection (methods)
• Middle Aged