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Abstract: PO1425

Collapsing FSGS or Crescentic GN or Both: A Diagnostic Challenge

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Malek, Irshadjahan, Division of Nephropathology, University of North Carolina, Chapel Hill, North Carolina, United States
  • Singh, Harsharan Kaur, Division of Nephropathology, University of North Carolina, Chapel Hill, North Carolina, United States
  • Nickeleit, Volker, Division of Nephropathology, University of North Carolina, Chapel Hill, North Carolina, United States
Introduction

The finding of an ANCA associated necrotizing & crescentic GN with collapsing FSGS is a rarity with only few reported cases in literature.

Case Description

A 53-yr-old AA female was admitted to hospital with difficulty in swallowing, poor oral intake, hemoptysis & AKI superimposed on CKD-III with hx of HTN & use of NSAIDs. Urine analysis showed hematuria, proteinuria & UPC ratio of 4.15. Blood analysis showed S.Cr 8.7mg/dl, BUN 60mg/dl, Albumin 2.4gm/dl, positive MPO ANCA & ANA titers. By light microscopy 36 glomeruli were present, 20% showed cellular/fibro-cellular crescent formation with underlying tuft fibrinoid necrosis & 20% showed collapsing FSGS. ATI, moderate IF/TA & moderate to severe arteriosclerosis were present. EM showed global podocyte activation with foot processes effacement.

Discussion

Collapsing FSGS and ANCA associated GN can both present with abrupt onset AKI & proteinuria. No specific test exists to separate crescents from collapsing FSGS; therefore this daunting differentiation requires a high level of suspicion, often relegated to experience. Most useful morphologic features are summarized in table 1. In our case, AA race (possible APOL1 risk variants) & underlying severe arterionephrosclerosis (ischemia) are the most likely etiologies for the collapsing FSGS.

MorphologyCollapsing FSGSCrescentic GN
Tuft Collapse++-
Podocytes hyperplasia/hypertrophy++-
Parietal epithelial cell hyperplasia-++
Tuft fibrinoid necrosis-++
Fibrin in extra capillary space+/-++
Podocytes protein resorption droplets +++ +/-
Inflammatory cells in extra capillary proliferation -+
Spindle cell elements/Myofibroblasts-+
Extracellular matrix deposition ++
Interstitial inflammation +-/++
RBC casts -++
ATI++
Tubular microcystic dilation ++++/-

A-Tuft collapse(arrow), podocytes hyperplasia/hypertrophy. B- Fibrinoid necrosis (arrow) & crescent formation(Trichrome stain x20)