Kidney Week

Abstract: FR-PO0701

Exostosin 1/2-Positive Membranous Nephropathy Associated with Methicillin-Sensitive Staphylococcus aureus Lung Abscess: Where Are the Autoantibodies?

Session Information

• Glomerular Diseases: Membranous Nephropathy, FSGS, and Podocytopathies
  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

• Lorenzo Capps, Maria Jose, Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States

Maria Jose Lorenzo Capps, MD

• Vega Batista, Franklyn, Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States

Franklyn Vega Batista, MD

• Thota, Priyanka, Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States

Priyanka Thota, MD

• Djeagou F., Albine, Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States

Albine Djeagou F., MD, MPH

• Iglesias, Jose I., Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States

Jose I. Iglesias, DO, FASN

Introduction

Membranous nephropathy (MN) is commonly associated with autoantibodies against PLA2R or THSD7A. Newer antigens such as EXT1 and EXT2 have broadened the understanding of the disease spectrum.

Case Description

A 78-year-old man with history of hypertension and tobacco use disorder presented to the ED with 6 months of progressive dyspnea and 3 months of swelling of hands and feet that progressed to eyelids, abdomen, and legs, foamy urine and decreased urine output. Lab studies showed UA with 3+ protein, 3+ blood, and 143 RBC, UPCR 4.0 mg/mg, Cr 1.25 mg/dL, BUN 21 mg/dL, and albumin 1.6 g/dL. Serology evaluation including PLA2R was negative. CT chest showed a lung mass that was biopsied and found to be a lung abscess which grew MSSA. Kidney biopsy showed MN with mesangial proliferative, segmental endocapillary proliferative, and exudative features, consistent with EXT2-associated MN. IF staining for PLA2R was negative.

Discussion

EXT1/EXT2-associated MN is typically seen in association with AI disease. In current literature no serum anti-exostosin antibodies have yet been isolated. In most reports, EXT1/EXT2 positivity reflects a secondary AI pattern rather than infection, malignancy, or medication exposure. This case is unusual because the patient had EXT2-positive MN in the setting of a proven infection. The temporal relationship raises the possibility that chronic infection contributed to antigen expression, immune-complex formation, or glomerular deposition. Another possibility is that the lung abscess was coincidental and unrelated. To our knowledge, this is the first reported case of EXT1/EXT2-positive MN associated with MSSA lung abscess. This expands the differential diagnosis for EXT-associated MN and suggests that infection should be considered during evaluation. Further reports are needed to clarify whether infection can trigger EXT-related glomerular injury or whether this represents a coincidental coexistence.