Abstract: FR-PO0708
Unsolved Mysteries: A Case of Isolated Podocyte Infolding Glomerulopathy
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
- Mathew, Neethu, Cleveland Clinic, Cleveland, Ohio, United States
- Lazor, Jennifer A., Cleveland Clinic, Cleveland, Ohio, United States
Introduction
Podocyte infolding glomerulopathy (PIG) is a rare entity with findings of diffuse podocyte infolding along the glomerular basement membrane (GBM) with invagination of microtubules and microsherules. It is often associated with autoimmune diseases, especially lupus. A small percent of cases occur without immune-complex findings, thus are isolated. We present a case of isolated PIG.
Case Description
A 52-year-old female with history of solitary kidney presented with worsening renal function and edema. Serological workup demonstrated a + ANA, + dsDNA, low C3/C4, and 6 g of proteinuria with a creatinine of 2.1 mg/dl and albumin 1.9 g/dL. Renal biopsy demonstrated 20 glomeruli, 4 globally sclerotic, 5 segmentally sclerotic, remaining with mesangial expansion, segmentally thickened capillary walls and scattered "holes" on silver stain. Mild acute tubular injury with 40% tubular atrophy and interstitial fibrosis noted. Immunofluorescence (IF) revealed segmental granular tubular BM staining with IgG (1+), C3 (1+), kappa (1+), and lambda (1+). All other stains were negative. A “full house” pattern was not identified. Electron microscopy (EM) revealed diffuse thickening of the GBM, infolding of the podocyte cytoplasmic processes, and membrane bound microsherules and tubules. Due to the overlap between membranous nephropathy with microsherules and PIG, the paraffin block was for mass spectrometry for membranous antigen typing. Testing was declined as findings were not consistent with membranous nephropathy. Rituximab and steroids were initiated for management.
Discussion
We report a case of isolated PIG. Etiology is unknown. Studies show a decrease in ACTN4 protein which serves as an actin crosslinking cytoskeletal protein for maintaining podocyte structure. While it typically responds to Rituximab and steroids, our patient did not respond favorably. Further research of this rare condition needs to be performed to assist in management strategies for isolated cases.
Acknowledgment
Michael Kuperman MD, Cleveland Clinic, OH (Provided pathology expertise and guidance)
Image 1: Infolding of the podocytes, Image 2: Membrane bound microsherules