Kidney nontumor
Microscopic polyangiitis

Topic Completed: 3 December 2012

Minor changes: 13 February 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Microscopic polyangiitis [title] kidney pathology

Nikhil Sangle, M.D.
Page views in 2019: 1,446
Page views in 2020 to date: 532
Cite this page: Sangle N. Microscopic polyangiitis. website. Accessed June 4th, 2020.
Definition / general
  • Systemic, pauci-immune, small vessel necrotizing vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA), often targeting myeloperoxidase (MPO), but without immune complex deposition or granulomas
  • A type of pauci-immune vasculitis (necrotizing small vessel vasculitis with no immune complex deposition by EM or immunofluorescence)
  • Previously considered a type of polyarteritis nodosa (eMedicine: Microscopic Polyangiitis [Accessed 17 January 2018])
Clinical features
  • Affects 1 per 100,000; any age but more common at age 50+ years
  • 90% have renal involvement; lungs usually affected (may simulate Goodpasture syndrome)
  • Also skin, ear, nose, throat, musculoskeletal, nervous system, GI
  • Symptoms: hematuria, proteinuria, hemoptysis, palpable purpura, abdominal pain, myalgias, arthralgias, mild hypertension
  • Birmingham Vasculitis Activity Score (BVAS, online calculator): useful for determining disease activity and outcome (Clin Rheumatol 2011;30:1499)
  • Survival of 60 - 80% at 10 years, death mainly in first months after diagnosis (Rheumatology (Oxford) 2011;50:1414)
  • Laboratory: PR3-ANCA (40%), MPO-ANCA (50%), negative (10%)
  • Treatment: IV corticosteroids, immunosuppressants, transplant (Clin J Am Soc Nephrol 2010;5:445, Am J Nephrol 2011;33:185)
Case reports
  • 59 year old man with myeloperoxidase-ANCA negative microscopic polyangiitis with pulmonary hemorrhage and IgA nephropathy (Case Rep Dermatol 2011;3:22)
Microscopic (histologic) description
  • Glomerulonephritis (focal and segmental to severe diffuse and crescentic)
  • Arterial lesions usually all at same stage
  • Usually tubulointerstitial infiltrate
  • Sausage shaped microaneurysms of interlobular arteries
  • No granulomas or asthma (Hum Pathol 1998;29:223)
Microscopic (histologic) images

Images hosted on other servers:
Missing Image

Mild mesangial cellular proliferation
and expansion; mesangial and
diffuse IgA deposits were observed
but crescents were absent
Missing Image

Red blood cell cast (urine)

Immunofluorescence description
  • No deposits
Electron microscopy description
  • No deposits
Differential diagnosis
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