Glomerulonephritis Overview

Glomerulonephritis Summary

• Postinfectious glomerulonephritis:

  • Clinical presentation: Nephritic syndrome
  • Pathogenesis: Immune complex mediated, circulating or planted antigen.
  • Glomerular pathology: Diffuse endocapillary proliferation, leukocytic infiltration.
  • Light microscopy: Granular IgG and C3 in GBM and mesangium, granular IgA in some cases.
  • Electron microscopy: Primarily subepithelial humps; subendothelial deposits in early disease stages.

• Crescentic (rapidly progressive) glomerulonephritis:

  • Clinical presentation: Nephritic syndrome, rapid progression.
  • Pathogenesis: Anti-GBM antibody mediated, immune complex mediated, ANCA mediated and unknown.
  • Glomerular pathology: Extracapillary proliferation with crescents, necrosis.
    • In anti-GBM antibody mediated GN: Linear IgG and C3 in the GBM.
    • In immune complex mediated: Granular IgG, other Igs, and/or complement in glomerular basement membrane.
    • In ANCA mediated GN: No deposits.
  • Electron microscopy: No deposits in anti-GBM and ANCA mediated GN, immune complexes at various locations in immune complex mediated GN.

• Membranous nephropathy:

  • Clinical presentation: Nephrotic syndrome.
  • Pathogenesis: In situ immune complex formation involving PLA2R antigen in most primary cases.
  • Glomerular pathology: Diffuse capillary wall thickening.
  • Pathology findings: Granular IgG and C3, diffuse, subepithelial deposits.

• Minimal change disease:

  • Clinical presentation: Nephrotic syndrome.
  • Pathogenesis: Unknown; loss of glomerular polyanion, podocyte injury.
  • Glomerular pathology: Normal findings; lipid in tubules.
  • Pathology findings: effacement of foot processes; no deposits

• Focal segmental glomerulosclerosis:

  • Clinical presentation: Nephrotic syndrome, non-nephrotic proteinuria.
  • Pathogenesis: Unknown; also, ablation nephropathy and podocyte injury are factors implicated.
  • Glomerular pathology: Focal and segmental sclerosis and hyalinosis.
  • Potential findings: IgM + C3 in many cases.

• Membranoproliferative glomerulonephritis (MPGN) type I:

  • Clinical Presentation: Nephritic/nephrotic syndrome.
  • Pathogenesis: Immune complex mediated.
  • Glomerular Pathology: Mesangial proliferative or membranoproliferative patterns of proliferation; GBM thickening; splitting.
  • Pathology Findings: IgG ++ C3; C1q ++ C4, subendothelial deposits.

• Dense-deposit disease (MPGN type II):

  • Clinical presentation: Hematuria, chronic renal failure.
  • Pathogenesis: Acquired or genetic dysregulation of the alternative complement pathway.
  • Glomerular pathology: Mesangial proliferative or membranoproliferative patterns of proliferation; GBM thickening; splitting.
  • Pathology Findings: C3; no C1q or C4; dense deposits.

• IgA nephropathy:

  • Clinical presentation: Recurrent hematuria or proteinuria.
  • Pathogenesis: Unknown.
  • Glomerular pathology: Focal mesangial proliferative glomerulonephritis; mesangial widening.
  • Pathology Findings: IgA ± IgG, IgM, and C3 in mesangium; mesangial and paramesangial dense deposits.

Abbreviations

• ANCA: Antineutrophil cytoplasmic antibodies
• GBM: Glomerular basement membrane
• IgG: Immunoglobulin G
• IgM: Immunoglobulin M
• PLA2R: Phospholipase A2 receptor