Microscopic polyangiitis

Last updated: December 8, 2022

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Microscopic polyangiitis (MPA) is an ANCA-associated small-vessel vasculitis. Typical clinical features include pulmonary vasculitis, pauci-immune glomerulonephritis, and palpable purpura. ANCAs (most commonly MPO-ANCAs) are present in up to 75% of patients with MPA. CT chest is indicated in all patients with pulmonary symptoms and often reveals ground-glass opacifications or nodular lesions. Biopsy is required to confirm the diagnosis; histopathology findings include fibrinoid necrosis without granulomas. Management involves immunosuppressive agents (e.g., glucocorticoids plus a glucocorticoid-sparing agent such as rituximab or methotrexate). Plasmapheresis may be considered for patients with severe disease.

Clinical features are very similar to those of granulomatosis with polyangiitis (GPA), but MPA spares the vessels in the upper respiratory tract (no sinusitis or rhinitis). [3]

Diagnosis is primarily clinical and confirmed by biopsy. Chest imaging is required for all patients with lower respiratory symptoms.

Microscopic PolyAngiitis has MyeloPeroxidase Antibodies (i.e., pANCA).

The absence of granulomas on histopathology plus pANCA positivity helps differentiate MPA from GPA, as they have very similar clinical features. [3][4]

General principles [3][5][6]

Pharmacotherapy [6]

Plasmapheresis [6]

Supportive care

  1. Kasper DL, Fauci AS, Hauser SL, Longo DL, Lameson JL, Loscalzo J. Harrison's Principles of Internal Medicine. McGraw-Hill Education ; 2015
  2. Rose NR, Mackay IR. The Autoimmune Diseases. Academic Press ; 2006
  3. Greco A, De Virgilio A, Rizzo MI, et al. Microscopic polyangiitis: Advances in diagnostic and therapeutic approaches. Autoimmun Rev. 2015; 14 (9): p.837-844. doi: 10.1016/j.autrev.2015.05.005 . | Open in Read by QxMD
  4. Sharon A. Chung, MD, MAS and Philip Seo, MD, MHS. Microscopic Polyangiitis. Rheumatic diseases clinics of North America. 2010 .
  5. Yates M, Watts RA, Bajema IM, et al. EULAR/ERA-EDTA recommendations for the management of ANCA-associated vasculitis. Ann Rheum Dis. 2016; 75 (9): p.1583-1594. doi: 10.1136/annrheumdis-2016-209133 . | Open in Read by QxMD
  6. Chung SA, Langford CA, Maz M, et al. American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Antineutrophil Cytoplasmic Antibody–Associated Vasculitis. Arthritis Care Res. 2021; 73 (8): p.1088-1105. doi: 10.1002/acr.24634 . | Open in Read by QxMD

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