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Microscopic Polyangiitis

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Microscopic Polyangiitis, Microscopic Polyarteritis, Leukocytoclastic Vasculitis, Hypersensitivity Vasculitis

  • See Also
  1. Small Vessel Vasculitis
  • Epidemiology
  1. Most common ANCA-associated Small Vessel Vasculitis
  2. Age of onset peaks at 40 to 60 years
  3. Gender: Men more commonly affected
  • Symptoms
  1. Fever
  2. Arthralgias and Myalgias
  3. Cough (Hemoptysis may be present)
  • Signs
  1. Renal involvement most common (Glomerulonephritis)
  2. Palpable Purpura
  3. Lung disease (Pulmonary Hemorrhage)
  • Differential Diagnosis
  1. Polyarteritis Nodosa
  2. ANCA-associated Small Vessel Vasculitis
    1. Especially pulmonary-renal syndromes
    2. Granulomatosis with Polyangiitis (previously known as Wegener's Granulomatosis)
    3. Systemic Lupus Erythematosus
    4. Anti-glomerular basement membrane disease
  • Labs
  1. Antineutrophil Cytoplasmic Antibody (ANCA)
    1. pANCA (MPO-ANCA) positive in 60-85% of cases
    2. cANCA (PR3-ANCA) positive in 40% of cases
  • Diagnostics
  1. Biopsy shows minimal to no immune vascular deposits
  • Management
  1. Same as Wegener's Granulomatosis
  • References
  1. Calabrese in Ruddy (2001) Kelly's Rheum, p. 1176-8
  2. Schoen in Cotran (1999) Robbins Pathology, p. 521-2