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Abstract: TH-PO471

A Case of Anti-Brush Border Antibody Disease

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation

Authors

  • Salupo, Nicholas W., Kettering Health, Dayton, Ohio, United States
  • Biederman, Laura, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Jackson, Jennifer L., Kettering Health, Dayton, Ohio, United States
Introduction

Anti-brush border antibody (ABBA) disease is a rare disorder characterized by tubulointerstitial damage due to antibodies against the renal proximal tubular brush border. IgG-containing deposits are found in the tubular basement membrane (TBM) and glomerular subepithelial space. Detection of anti-megalin (LRP2) antibodies is pathognomonic. There is not much evidence detailing this condition.

Case Description

A 65 year old male with hypertension, peripheral vascular disease, hepatitis C, and benign prostatic hypertrophy with worsening GFR after acute kidney injury. Serum creatinine was 1.8-2.0 mg/dL. There was no hematuria, proteinuria, or urinary eosinophilia. He had normal complements, antinuclear antibody was negative, no monoclonal proteins were seen on SPEP, urinary kappa lambda light chain ratio was 1.26, and unremarkable imaging. Kidney biopsy showed moderate chronic parenchymal changes with many TBM and Bowman’s capsule electron dense deposits immunoreactive for polyclonal IgG and glomerular segmental, subepithelial electron dense deposits with membranous pattern immunodominant for polyclonal IgG. Anti-megalin staining was positive along tubular basement membranes.

Discussion

This case demonstrates a rare, but possibly increasing, disease process. The inciting cause remains unknown but the differential diagnosis includes systemic lupus erythematosus, Sjögren's syndrome, idiopathic hypocomplementemic tubulointerstitial nephritis, and IgG4-related disease. Biopsy findings of TBM deposits on the apical aspect of the TBM are most suspicious for anti-brush border antibody disease. Definitive diagnosis is made with the anti-megalin staining. Treatment, necessary if impaired renal function persists, consists of immunosuppression to stall further renal deterioration.

Tubular basement membrane deposits on the luminal aspect of TBM