microscopic polyangiitis
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Introduction
Term introduced in 1948 to describe disorder considered different from polyarteritis nodosa (PAN). Alias microscopic PAN.
Epidemiology
(similar to PAN)
- males affected more frequently than females
- median age of onset is 50 years
Pathology
- vulnerable organs include:
- kidneys (~80%)
- joints (~70%)
- skin (~50%)
- gastrointestinal tract (~40%)
- lungs (~20%)
- peripheral nerves (~20%)
- shares some features with Wegener's granulomatosis & polyarteritis nodosa (PAN)
- distinguishing features from Wegener's granulomatosis:
- involves skin in ~50% of patients[3]
- distinguishing features from PAN:
- few or no immune complexes (pauci-immune)
- disease affects small vessels
- glomerulonephritis
- rapidly progressing
- focal & segmental
- necrotizing without granulomatosis
- inflammation of the pulmonary capillaries
- pulmonary alveolar hemorrhage (12-30%)
Clinical manifestations
- characteristically affects lungs & kidneys[4]
- hypertension
- weight loss
- arthralgias, myalgias
- peripheral neuropathy
- mononeuritis multiplex
- distal symmetric polyneuropathy
- CNS:
- epididymitis
- skin
- abdominal pain, GI bleeding
- sinusitis
- sensorineural hearing loss
Diagnostic criteria
- diagnostic considerations are similar to PAN
Laboratory
- p-ANCA (MPO Ab) is positive in 75% (similar to PAN)[4]
- c-ANCA (proteinase-3 Ab) may be positive
- urinalysis
- azotemia
- anemia
- complement levels are normal
- erythrocyte sedimentation rate (ESR) commonly > 100 mm/hr
- renal biopsy not angiography best for diagnosis
- open lung biopsy if no renal manifestations
- transbronchial lung biopsy generally does not provide sufficient tissue for diagnosis[4]
- skin biopsy
- see ARUP consult[5]
Radiology
Differential diagnosis
- Wegener's granulomatosis characterized by cANCA
- microscopic polyangiitis involves skin in ~50% of patients[3]
- polyarteritis nodosa (PAN)
- see Pathology: for distinguishing features from PAN
Management
- induction therapy (initial treatment)
- combination therapy
- rituximab 375 mg/m2/week (4 doses) in combination with glucocorticoids preferred induction for severe disease[8]
- methotrexate in combination with glucocorticoid preferred induction for less severe disease[8]
- prednisone + cyclophosphamide to induce remission
- treatment for 3-6 months
- maintenance therapy with methotrexate or azathioprine[4]
- rituximab in combination with glucocorticoids if cyclophosphamide is contraindicated, not tolerated, or is otherwise unacceptable (NICE) [NGC]
- mycophenolate acceptable for maintenance therapy
- azathiaprine acceptable for maintenance therapy[4]
- plasmapheresis may delay need for dialysis[4]
- management considerations are similar to PAN
More general terms
Additional terms
References
- ↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1912-14
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 610, 785
- ↑ 3.0 3.1 3.2 Khasnis A and Langford CA. Update on vasculitis. J Allergy Clin Immunol 2009 Jun; 123:1226. PMID: https://www.ncbi.nlm.nih.gov/pubmed/19501230
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Medical Knowledge Self Assessment Program (MKSAP) 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 2006, 2009, 2012, 2015, 2018, 2022.
Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022 - ↑ 5.0 5.1 ARUP Consult: Microscopic Polyangiitis The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/microscopic-polyangiitis
- ↑ Ramsey J, Amari M, Kantrow SP. Pulmonary vasculitis: clinical presentation, differential diagnosis, and management. Curr Rheumatol Rep. 2010 Dec;12(6):420-8 PMID: https://www.ncbi.nlm.nih.gov/pubmed/20882372
- ↑ Kallenberg CG. The diagnosis and classification of microscopic polyangiitis. J Autoimmun. 2014 Feb-Mar;48-49:90-3. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/24461388
- ↑ 8.0 8.1 8.2 Chung SA, Langford CA, Maz M et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Rheumatol 2021 Aug; 73:1366-1383. PMID: https://www.ncbi.nlm.nih.gov/pubmed/34235894 https://onlinelibrary.wiley.com/doi/10.1002/art.41773
Patient information
ANCA-associated vasculitis (microscopic-polyangiitis) patient information