Kidney Week

Abstract: FR-PO0787

When "Pauci-Immune" Is Not: Masked IgG Kappa Deposits in Crescentic and Necrotizing Glomerulonephritis

Session Information

• Glomerular Diseases: ANCA Vasculitis, Anti-GBM Disease, and Crescentic GN
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Jazayeri, Anna Margaret, South Georgia Medical Center, Valdosta, Georgia, United States

Anna Margaret Jazayeri, MD

• Sharma, Shaleekha, South Georgia Medical Center, Valdosta, Georgia, United States

Shaleekha Sharma, DrMed

• Truong, Tai, South Georgia Medical Center, Valdosta, Georgia, United States

Tai Truong, MD

Introduction

Crescentic and necrotizing glomerulonephritis is most commonly attributed to pauci-immune vasculitis; however, a subset of cases harbor masked monoclonal immunoglobulin deposits. We present a case of crescentic glomerulonephritis in which additional pathologic evaluation revealed masked IgG kappa deposits.

Case Description

A 25-year-old healthy AAF presented with complaints of months of facial and peri-orbital swelling. Admitted with acute kidney injury, serum creatinine of 1.8 mg/dL (baseline was 0.50 mg/dL), and acute cystitis. Urinalysis demonstrated nephrotic-range proteinuria and hematuria, with a spot check urine protein-to-creatinine ratio of 2.54mg/g. Serologic evaluation, resulted +ANA, DS-DNA negative, and ANCA, anti-GBM antibodies, and complement levels were unrevealing. Infectious studies including HBV, HCV, HIV, and syphilis were negative. SPEP showed no monoclonal protein and ASO titer 176IU/ml.
Kidney biopsy showed focal crescentic and necrotizing glomerulonephritis on light microscopy. Immunofluorescence was negative for immune complex deposition, suggesting pauci-immune. Given the diagnostic discordance, paraffin immunofluorescence was performed with antigen retrieval. This revealed monotypic IgG kappa deposits along glomerular capillary loops and within the mesangium.
Patient was diagnosed with focal crescentic and necrotizing glomerulonephritis with masked IgG-kappa deposits.
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Discussion

Focal crescentic and necrotizing glomerulonephritis with masked IgG kappa deposits is a rare and underrecognized condition. Its pathophysiology remains incompletely understood, and there are no established treatment guidelines.

Crescentic Necrosis

Paraffin Immunofluorescence -Kappa