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Kidney Week

Abstract: PO2009

Podocyte Infolding Glomerulopathy: New Disease or Pattern of Injury?

Session Information

  • Podocyte Biology
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Report

  • 1204 Podocyte Biology

Authors

  • Guntupalli, Sri Vibhavari, Saint Vincent Hospital, Worcester, Massachusetts, United States
  • Martin, Suzanne G., Saint Vincent Hospital, Worcester, Massachusetts, United States
Introduction

Occasional podocyte infolding is reported in membranous nephropathy, but global and diffuse infolding is rare. Whether this is a new disease entity or a pattern of podocyte injury may influence therapy.

Case Description

52 year-old-male with hypertension developed lower extremity edema, pleuritic chest pain and dyspnea. CT chest showed bilateral pulmonary emboli. Creatinine was 0.92 mg/dL, cholesterol 239 mg/dL, albumin 3.2 g/dL, urine protein:Cr ratio 32,647 mg/gCr. Renal biopsy showed immune complex deposition in a membranous pattern, and subepithelial deposits with targetoid microvesicular substructures, suggesting a podocyte infolding glomerulopathy (PIG) [Fig.1 Electron microscopy showing PIG]. Immune deposits were dominantly reactive for IgG4, and also for other IgG subclasses, C3, IgM, and kappa and lambda light chains. Deposits were reactive for PLA2R. Serum PLA2R antibody and other serologies were negative. He was anticoagulated and treated for 6 months with the modified Ponticelli protocol. Creatinine remains normal, but hypoalbuminemia and proteinuria (190mg – 1.2g) persist 8 months after starting treatment.

Discussion

In 1985, Dales and Wallace [1] described massive deposits of spherular organelles in the subepithelial space of glomerular capillary walls in a patient with membranous nephropathy. In 2008, Joh et al [2] studied 25 Japanese patients with microspheres and microtubular structures associated with podocyte infolding, coining the term “podocyte infolding glomerulopathy.” Rare cases are reported in India, Latin America, and Europe.

It is unclear whether PIG is a subtype of membranous nephropathy or a distinct glomerular lesion. Identification of PIG associated with vesicoureteral reflux, myeloma, and autoimmune diseases, and the absence of immune complexes in many biopsies, suggest a distinct type of podocyte injury. Ultimately, the pathophysiology of PIG is not understood.

Response to therapy and prognosis are not well-described. This patient was treated with the modified Ponticelli protocol, given findings of membranous nephropathy, with a reduction in proteinuria but not full remission. This may represent a partial response to therapy or may imply that podocyte infolding glomerulopathy is a separate disease entity not responsive to immunosuppression.