Membranoproliferative Glomerulonephritis: The Role for Laser Microdissection and Mass Spectrometry

作者：Jain Deepika^*; Green Jamie A; Bastacky Sheldon; Theis Jason D; Sethi Sanjeev

来源：American Journal of Kidney Diseases, 2014, 63(2): 324-328.

DOI：10.1053/j.ajkd.2013.09.007

• Membranoproliferative glomerulonephritis
• monoclonal gammopathy
• laser microdissection
• laser-capture microdissection-mass spectrometry (LCM-MS)
• mass spectrometry
• proteomics
• nephrotic
• proteinuria

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 5,000 mg/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 electrondense deposits. The workup excluded an infectious or autoimmune disease, but IgG kappa monoclonal protein was detected in serum at a concentration of 0.4 mg/dL. Because there was a mismatch between the serum monoclonal protein (IgG kappa) 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 kappa, 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.

• 出版日期2014-2