Renal-Limited Cryofibrinogen-Associated Glomerulonephritis Diagnosed Using Electron Microscopy

Nephrology (Carlton). 2026 Apr;31(4):e70189. doi: 10.1111/nep.70189.

Abstract

Cryofibrinogen-associated glomerulonephritis (CryoFiGN) is a rare, diagnostically challenging cause of nephrotic syndrome, and its clinical presentation can vary considerably. Herein, we report the case of a 76-year-old man who presented with nephrotic syndrome; biopsy showed a C3-dominant membranoproliferative pattern of injury. Electron microscopy revealed organised subendothelial microtubular deposits (40-80 nm), confirming CryoFiGN, despite inconclusive results on mass spectrometry. The patient progressed to end-stage kidney disease and later developed systemic vasculitis with skin ulcers and gastrointestinal bleeding. CryoFiGN may initially manifest as a renal-limited disease and evolve into systemic vasculitis. Electron microscopy is pivotal for diagnosis when proteomic analysis is inconclusive and long-term surveillance is warranted.

Keywords: cryofibrinogen‐associated glomerulonephritis; electron microscopy; end‐stage kidney disease; nephrotic syndrome; systemic vasculitis.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Biopsy
  • Cryoglobulinemia* / complications
  • Cryoglobulins* / analysis
  • Fibrinogens, Abnormal*
  • Glomerulonephritis* / pathology
  • Humans
  • Kidney Failure, Chronic / etiology
  • Kidney* / ultrastructure
  • Male
  • Microscopy, Electron*
  • Nephrotic Syndrome* / diagnosis
  • Nephrotic Syndrome* / etiology
  • Predictive Value of Tests

Substances

  • cryofibrinogen
  • Cryoglobulins
  • Fibrinogens, Abnormal