Abstract: SA-PO0751
A Unique Case of Phospholipase A2 Receptor (PLA2R) Antibody- and NELL-1-Positive Lupus Membranous Nephritis
Session Information
- Glomerular Diseases: Lupus Nephritis, Monoclonal Gammopathy-Related Disease, and Transplantation
October 24, 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
- Penny, Michael, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
- Ancell, Kaitlyn Santineau, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
- Monk, Brian Christopher, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
- Zeitler, Evan, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
Introduction
Membranous nephropathy (MN) is the most common cause of non-diabetic nephrotic syndrome. Several target antigens have been discovered in MN, and assessing antibody positivity can further categorize MN into primary or secondary etiologies. We present a patient with biopsy consistent with lupus membranous nephritis (LMN) and immunofluorescence (IF) positive for PLA2R and NELL1 antigens. This is a rare combination, and possibly the first reported dual-antigen MN secondary to lupus.
Case Description
54-year-old male presented with 1.5 months of peripheral edema and weight gain. On exam, he had right knee swelling. Laboratory evaluation revealed a urinalysis with 3+ protein and moderate blood with monomorphic red cells on sediment exam. Urine protein-to-creatinine ratio was 9.61. Serum creatinine was 1.2 mg/dL from baseline of 0.7 mg/dL. Lupus serologies and serum PLA2R and thrombospondin antibodies were negative. CT chest/abdomen/pelvis was negative for malignancy. Renal biopsy showed membranous and diffuse proliferative glomerulonephritis. Electron microscopy revealed diffuse podocyte activation and rare tubuloreticular inclusions (left panel). IF showed a full house pattern; tissue stained positive for PLA2R (middle panel) and NELL1 (right panel). He was treated with pulse dose steroids, a prednisone taper, mycophenolate, and tacrolimus. Creatinine normalized though proteinuria persisted at 3 month follow up.
Discussion
PLA2R and NELL1 are the two most common antigens in primary MN, present in 70% and 10% of cases, respectively. NELL1 also has secondary associations, with ⅓ of patients with NELL1-positive MN having an underlying malignancy. Despite positivity for PLA2R and NELL1, biopsy findings in this case including full house IF, proliferative features, and tubular inclusion bodies are more suggestive of LMN. Notably, LMN is predominantly positive for exostosin 1/2, seen in up to 45% of cases though not here. Patients with dual positivity take longer to achieve remission and clinical outcomes on these patients are lacking. This case demonstrates that while antigen staining in MN provides value in diagnosis, prognosis, and treatment, the known associations of identified antigens do not preclude alternative diagnoses.