Abstract: TH-PO968
Laser Microdissection and Tandem Mass Spectrometry, a Valuable Method to Identify Components of Glomerular Deposition Diseases: A Case Report
Session Information
- Glomerular Trainee Case Reports
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1203 Glomerular Diseases: Clinical, Outcomes, and Trials
Authors
- Shinya, Kotoko, University of Miyazaki, Miyazaki, Japan
- Minakawa, Akihiro, University of Miyazaki, Miyazaki, Japan
- Ishizaki, Yuri, University of Miyazaki, Miyazaki, Japan
- Aso, Kumiko, University of Miyazaki, Miyazaki, Japan
- Nishizono, Ryuzoh, University of Miyazaki, Miyazaki, Japan
- Kikuchi, Masao, University of Miyazaki, Miyazaki, Japan
- Inagaki, Hiroko, University of Miyazaki, Miyazaki, Japan
- Sato, Yuji, University of Miyazaki, Miyazaki, Japan
- Fujimoto, Shouichi, University of Miyazaki, Miyazaki, Japan
Introduction
The diagnosis of glomerular deposition diseases (GDDs), including proliferative glomerulonephritis with monoclonal IgG deposition (PGNMID), requires evidence of pathogenic deposits in the glomerulus. Laser microdissection (LMD) and Tandem mass (MS/MS) spectrometry, which can identify the deposit’s structure, might be valuable for this purpose in theory. Here, we report a case of PGNMID suggesting the applicability of MS/MS spectrometry in the diagnosis of GDDs.
Case Description
A 38-year-old woman was admitted to our department with a 7-month history of moderate proteinuria and without a history of hematological disease. A 24 hour urinary test showed proteinuria excretion of 1.2 g/day with no microscopic hematuria. A blood test showed 0.63 mg/dL of creatinine, 5.98 g/dL of total protein and 3.54 g/dL of albumin. Cryoglobulinemia was not detected. A renal biopsy showed membranous nephropathy by light microscopy together with granular deposits in subendothelial, subepithelial, and intra-glomerular basement membranes by electron microscopy. An immunofluorescence (IF) study showed restricted IgG1-Kappa deposition, which was validated by MS/MS spectrometry using several glomerulus dissected by LMD from a paraffin-embedded specimen, which showed an IgG1-heavy chain and Kappa-chain variable lesion. Therefore, we were able to diagnose the patient with PGNMID, and initiate treatment with an angiotensin converting enzyme inhibitor. The patient’s renal function has been stable up until the time of writing this report.
Discussion
In the current case, we found that the pathogenic deposit shown by immunostaining was consistent with the result of MS/MS spectrometry. Based on the observations of this case, we validated MS/MS spectrometry’s ability to detect deposits. The evidence of pathogenic deposits is critical in the diagnosis of GDDs. Although IF is commonly used, this process can only test for a limited number of deposit antigens. In theory, LMD and MS/MS spectrometry could detect a broader spectrum of deposit and might enable a better understanding of GDDs.
<Acknowledgment> LMD and MS/MS analysis was performed by Drs. Yoshinaga, Yazaki, Sekijima (Shinshu University)