Kidney nontumor
Associated with systemic conditions
Microscopic polyangiitis

Author: Nikhil Sangle, M.D. (see Authors page)

Revised: 11 July 2018, last major update December 2012

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Microscopic polyangiitis [title] kidney pathology

Cite this page: Sangle, N. Microscopic polyangiitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/kidneymicroscopicpolyangiitis.html. Accessed August 18th, 2018.
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
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Red blood cell cast (urine)

Immunofluorescence
  • No deposits
Electron microscopy description
  • No deposits
Differential diagnosis
  • Other pauci-immune glomerulonephritis including:
    • Churg-Strauss syndrome / allergic granulomatosis and angiitis (eosiniophilia, asthma, granulomas)
    • Wegener’s granulomatosis (necrotizing granulomas)