Kidney Week

Abstract: TH-PO676

Phospholipase A2 Receptor (PLA2R)-Positive Membranous Nephropathy in a Patient with Negative PLA2R Serology

Session Information

• Glomerular Diseases: Case Reports - 1
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Quinones Vargas, Irmaris Raquel, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States

Irmaris Raquel Quinones Vargas, MD

• Avila, Paul Brandon, Universidad de San Carlos de Guatemala, Ciudad de Guatemala, Guatemala, Guatemala

Paul Brandon Avila, MD

• Teixeira, J. Pedro, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States

J. Pedro Teixeira, MD, FASN

• Caza, Tiffany, Arkana Laboratories, Little Rock, Arkansas, United States

Tiffany Caza, MD, PhD

• Garcia, Pablo, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States

Pablo Garcia, MD, FASN

Introduction

Recent advances in the understanding of the pathogenesis of membranous nephropathy (MN) led to the identification of several target antigens, including phospholipase A2 receptor (PLA2R). PLA2R antibodies are present in the majority of primary MN cases and have important implications for diagnosis, prognosis, and treatment. Here we present a case of MN negative for PLA2R antibodies but with positive biopsy staining for PLA2R.

Case Description

A 51-year-old man presented to clinic with nephrotic syndrome (NS) with lower extremity edema, serum creatinine 1.1 mg/dL, albumin 0.4 g/dL, 24-h urine protein of 13.2 g, and urine protein-creatinine ratio (UPCR) of 14 g/g. He was recently diagnosed with pulmonary embolism which was felt to be secondary to NS. All serologies, including HIV, hepatitis panel, C3, C4, ANCA, ANA, dsDNA, SPEP, UPEP, free light chains, and PLA2R by immunofluorescence assay (IFA), were negative. A kidney biopsy showed MN with glomerular PLA2R deposition by immunohistochemistry (Figure). He was treated with rituximab 1 g x 2 doses 2 weeks apart. A month later UPCR decreased to 7 g/g and serum albumin increased to 1.4 g/dL.

Discussion

Prior studies have suggested that negative PLA2R serology in patients with previously diagnosed PLA2R-positive MN indicates disease inactivity. However, this case suggests this is not always true. In particular, early in the course of MN PLA2R may be detected on biopsy despite a lack of circulating PLA2R antibodies. For scenarios highly suspicious for MN despite negative initial PLA2R serology, clinicians may consider alternative PLA2R antibody assays (e.g., enzyme-linked immunosorbent assay rather than IFA) as well as definitive biopsy diagnosis.