Pauci-Immune Glomerulonephritis

Epidemiology

  • First described in 1997
  • May represent a limited form of Microscopic Polyangiitis

Physiology

  • Vasculitis usually starts in kidney (may progress to DAH or systemic necrotizing vasculitis)

Pathology

  • Diffuse Alveolar Hemorrhage (DAH): pulmonary capillaritis
  • Glomerulonephritis: histologically similar to that of Wegener’s Granulomatosis and Microscopic Polyangiitis

Diagnosis

  • PFT’s: increased DLCO during DAH
  • FOB:
    • BAL: RBC’s/ hemosiderin-laden macrophages
  • OLB: may be necessary
  • CXR/Chest CT Patterns
    • Diffuse or patchy focal alveolar infiltrates:
    • Interstitial infiltrates: appear with chronic or recurrent DAH
  • ESR:
  • Serology
    • ANA:
    • Anti-DNA:
    • RF:
    • C3/C4/CH50:
    • p-ANCA (perinuclear pattern, targeted mainly against myeloperoxidase): may be positive (similar to Microscopic Polyangiitis)
    • Anti-GBM: negative
  • CBC:
  • Urinalysis: abnormal
  • Renal Bx: focal segmental necrotizing GLN/crescents
    • Tissue Ab staining: nearly void of immune complexes, minimal fibrin is only finding

Clinical Presentations

(pulmonary-renal syndrome, may be confused wth Goodpasture’s Syndrome)

Pulmonary Manifestations

  • Diffuse Alveolar Hemorrhage (see [[Diffuse Alveolar Hemorrhage]]): occurs in 50% of cases
    • Symptoms usually present for only days-weeks before presentation
    • Isolated pulmonary capillaritis was present in 8/29 patients from original 1997 study: these cases may be confued with Goodpasture’s syndrome
    • Hemoptysis: may be absent on initial presentation in some cases, even after significant bleed
    • Cough
    • Dyspnea
    • Chest Pain: may occur

Renal Manifestations

  • Glomerulonephritis

Treatment

  • Corticosteroids + Cytoxan (or Azathioprine): remission occurs in most patients

References

  • Jennings; Am J Resp Crit Care Med, 1997