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Abstract: PO1525

Diagnostic Dilemma: Glomerular Linear IgG Deposit with Negative Anti-GBM Antibody

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Gupta, Sonali, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Sambharia, Meenakshi, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Holanda, Danniele Gomes, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Safar, Elyas, Blessing Hospital, Quincy, Illinois, United States
  • Huang, Y-Chen, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
Introduction

Linear deposition of IgG along glomerular basement membrane (GBM) is hallmark of anti GBM glomerulonephritis. Subclass IgG 3 deposition is seen predominantly in these cases. Rare atypical anti-GBM cases have been described in literature as rare, indolent, no pulmonary involvement and undetectable antibodies. We describe a case of atypical anti GBM, four days after mRNA COVID vaccine.

Case Description

A 77-year-old male with history of hypertension presented with hypertensive emergency and acute kidney injury 4 days after first COVID vaccine (mRNA). Workup revealed sCr 2.6 mg/dl (1.5 mg/dl 1 month back), 3+ blood and 3+ protein by UA, normal C3, C4, ANA 1: 160, spot urine protein: creatinine- 2.2, serum albumin- 4g/dl. anti ds-DNA, ANCA and anti-GBM antibody was negative so was Hepatitis panel andHIV. Serum electrophoresis was negative for monoclonal protein. He did not have any pulmonary symptoms and CXR was negative for acute pathology. Renal biopsy was performed. LM: mild to moderate nodular mesangial expansion, mildly increased mesangial cellularity and focal segmental nodular mesangial sclerosis. IF showed positive linear global capillary loop staining with IgG (2+), with kappa (1+) and lambda (2+) co-staining. Trace mesangial IgM and granular C3 (trace1+) are also noted in the peripheral capillary loops. EM showed diffuse foot process effacement. Few subepithelial, intramembranous and mesangial electron dense deposits were seen. Additional IgG subclasses IF showed positive linear glomerular staining for IgG1 (3+), IgG2 (1+), IgG4 (1+), negative for IgG3.

Discussion

Although no definitive active glomerular crescents or necrotizing lesions were seen, positive linear IgG staining in the glomerular capillary loops was concerning for atypical anti-GBM disease in setting of negative antibody and negative IgG3A study looking at 20 atypical anti-GBM patients found that 1 year patient and renal survival was 93% and 85% respectively. A few patients in this study had biopsy findings of DFPE and sub-epithelial deposits like ours. There have been few reports of COVID vaccine unmasking glomerulonephritis. However, it needs further investigation.