Document Type

Conference Proceeding

Publication Date

9-2023

Publication Title

Archives of Pathology & Laboratory Medicine

Abstract

Context: In addition to monoclonal cryoglobulinemic glomerulopathy, nonorganized monoclonal immunoglobulin (Ig) can deposit in glomeruli, causing either proliferative glomerulonephritis or membranous glomerulopathy. We present our experience related to this phenomenon.

Design: Sixteen cases of monoclonal immunoglobulin-associated glomerulopathy (MIAGN) from 14 patients were identified during the past 13 years and their pathologic and clinical features were collected and presented.

Results: One case of membranous glomerulopathy with monoclonal immunoglobulin deposits (MGNMID) (also called membranous glomerulopathy with light-chain–restricted deposits) was found. The patient was a 71-year-old woman with serum creatinine at 0.7 mg/dL and nephrotic syndrome (urine protein to creatinine ratio at 5.41), but negative serum PLA2R. Free κ was slightly elevated, but the κ:λ ratio was normal. Immunoelectrophoresis and immunofixation were both negative for monoclonal protein. Immunofluorescence (IF) studies showed IgG (Figure 2.21, A) and κ staining (Figure 2.21, B) in the glomeruli with negative λ staining. Light microscopy (LM) showed mild thickening of the glomerular basement membranes (Figure 2.21, C). Electron microscopy (EM) revealed stage 1 and 2 deposits in the subepithelial spaces (Figure 2.21, D). The remaining 15 biopsies from 13 patients showed proliferative glomerulonephritis with monoclonal immunoglobulin deposits with a membranoproliferative pattern by LM, dominant IgG-κ staining by IF, and subendothelial/mesangial deposits by EM. Only 1/3 of these cases were found to be lymphoproliferative disorders as previously reported.

Volume

147

Issue

9

First Page

e61

Comments

College of American Pathologists 2023 Annual Meeting CAP23, October 7-10, 2023, Chicago, IL

DOI

10.5858/arpa.2023-0258-AB

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