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Microscopic polyangiitis
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Microscopic polyangiitis

Contributors: Vivian Wong MD, PhD, Catherine Moore MD, Susan Burgin MD, Michael W. Winter MD
Other Resources UpToDate PubMed


Microscopic polyangiitis (MPA) is an antineutrophil cytoplasmic antibody (ANCA)-associated disease resulting in multisystem necrotizing inflammation of small and medium-sized vessels without granuloma formation. It is associated with elevated perinuclear ANCA (p-ANCA) titers and a positive myeloperoxidase (MPO) antibody. The most common sites of involvement are the kidneys, with focal and segmental necrotizing crescentic glomerulonephritis, and the lungs, with pulmonary capillaritis and alveolar hemorrhage. The onset may be insidious or acute. Severe pulmonary or renal symptoms are considered a medical emergency, and immediate treatment is required.

MPA most often occurs in patients between ages 50 and 60 years, but cases have been reported in children and older adults as well. There is a slight male predominance. MPA is most common in patients of Northern European descent.

Complications of MPA include diffuse alveolar hemorrhage, interstitial lung disease, pleural effusion, pulmonary edema, pleuritis, interstitial fibrosis, rapidly progressive focal segmental necrotizing glomerulonephritis, gastrointestinal bleeding, colonic ulcerations, intestinal ischemia, bowel perforation, mononeuritis multiplex, and polyneuropathy.


M31.7 – Microscopic polyangiitis

1144805008 – Microscopic polyangiitis

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Granulomatosis with polyangiitis (GPA) – Presence of granulomatous inflammation and upper respiratory tract involvement.
  • Eosinophilic granulomatosis with polyangiitis – Associated with peripheral eosinophilia and a history of asthma.
  • Leukocytoclastic vasculitis
  • Sarcoidosis
  • Cryoglobulinemia
  • Cryofibrinogenemia
  • Systemic lupus erythematosus (SLE)
  • Polyarteritis nodosa
  • Coccidioidomycosis
  • Cocaine levamisole toxicity can often present with positive ANCA studies and may mimic vasculitides.
  • Drug-induced Vasculitis with positive ANCA studies (propylthiouracil, hydralazine, anti-tumor necrosis factor alpha, sulfasalazine, D-penicillamine, minocycline)
  • Deep fungal and Atypical mycobacterial infection infections (eg, Mucormycosis, Tuberculosis) – May have pulmonary symptoms that mimic GPA. Biopsy should demonstrate the causative organisms.
  • Pyoderma gangrenosum
  • Calciphylaxis
  • Oxalosis
  • Ecthyma gangrenosum
  • Chronic meningococcemia
  • Strongyloidiasis
  • Type 2 lepra reaction
  • Immunoglobulin A vasculitis
  • Leukemic vasculitis
  • Embolism (septic, Fat emboli, Air embolism, Cholesterol emboli, marantic)
  • Hypercoagulable state
  • Disseminated intravascular coagulation
  • Purpura fulminans
  • Warfarin necrosis
  • Deficiency of adenosine deaminase type 2
  • Other collagen vascular diseases (ie, Rheumatoid arthritis, Dermatomyositis)

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Last Reviewed:06/18/2020
Last Updated:07/27/2020
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Microscopic polyangiitis
A medical illustration showing key findings of Microscopic polyangiitis : Fever, p-ANCA positive, Palpable purpura, Anorexia, Arthralgia, Myalgia
Copyright © 2024 VisualDx®. All rights reserved.