Abstract: FR-PO0919
Rare Case of Podocyte Infolding Glomerulopathy in a Patient with Systemic Lupus Erythematosus
Session Information
- Glomerular Case Reports: Lupus, FSGS, Complement, and More
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Johnston, Samuel, University of Alabama at Birmingham Health System, Birmingham, Alabama, United States
- Konda, Raghunandan, University of Alabama at Birmingham Health System, Birmingham, Alabama, United States
- Fatima, Huma, University of Alabama at Birmingham Health System, Birmingham, Alabama, United States
- Rizk, Dana V., University of Alabama at Birmingham Health System, Birmingham, Alabama, United States
- Rajasekaran, Arun, University of Alabama at Birmingham Health System, Birmingham, Alabama, United States
Introduction
Podocyte Infolding Glomerulopathy (PIG) is an extremely rare glomerular disease characterized by cytoplasmic projections of podocytes into the glomerular basement membrane (GBM), seen primarily on electron microscopy (EM). Although rare and seen in 0.1% of kidney biopsies, most patients with PIG have underlying Systemic Lupus Erythematosus (SLE). Our case highlights consideration of this rare pattern of glomerular injury in SLE.
Case Description
A 45-year-old female with longstanding SLE [complicated by leukopenia, thrombocytopenia, pericarditis] treated with mycophenolate mofetil, SC belimumab, hydroxychloroquine, and prednisone presented with non-oliguric AKI with concern for nephritic pattern of glomerular injury. Serum creatinine [SCr] was 1.6 mg/dL (baseline 1.2 mg/dL), serum albumin of 3.3 mg/dL, and UPCR 1.9 g/g. Urinalysis revealed acanthocytes. ANA 1:320, Anti-smith 112 units, with negative anti-dsDNA. Rest of comprehensive GN workup were negative. Kidney biopsy demonstrated a membranous pattern of injury with rare subepithelial and intramembranous immune complex deposits [modified NIH activity and chronicity indices of 0/24 and 2/12, respectively]. Focal immune complex staining involving <50% of capillary loops with granular polytypic IgG staining along tubular basement membranes seen on IF. EM revealed segmental podocyte cytoplasmic invaginations into the GBM suggestive of PIG. In addition to her ongoing SLE treatment, intravenous rituximab [2 doses of 1g two weeks apart] was administered. After 7 months, SCr returned to baseline with a bland urinalysis.
Discussion
Our case highlights the pathological complexity of PIG leading to AKI and subnephrotic range proteinuria in a patient with underlying SLE. PIG is a distinct morphologic entity that falls outside the traditional ISN/RPS lupus nephritis classes . PIG is classified by the Japanese Society of Nephrology into 3 subtypes based on microstructures in the GBM, primary podocyte infoldings, or both. Although the exact pathogenesis of PIG remains unclear, recent laser microdissection and mass spectrometry analysis have revealed dysregulation of podocyte cytoskeletal protein ACTN4 and tubulin beta-4 chain. PIG has relatively good outcomes following immunosuppression. Further investigation is warranted into its pathogenesis, clinical significance, and optimal management.