| Microscopic polyangiitis | |
|---|---|
| Classification and external resources | |
| ICD-10 | M31.7 |
| DiseasesDB | 8193 |
| eMedicine | med/2931 |
Microscopic polyangiitis (MPA) is an ill-defined autoimmune disease characterized by pauci-immune, necrotizing, small-vessel vasculitis without clinical or pathological evidence of necrotizing granulomatous inflammation.
Contents |
Presentation
Because many different organ systems may be involved, a wide range of symptoms are possible in MPA.
Purpura and livedo may be present.[1]
Diagnosis
Laboratory tests show an increased sedimentation rate, reduced red blood count, antineutrophil cytoplasmic antibodies (p-ANCA) directed against myeloperoxidase[2] (a constituent of neutrophil granules), and protein and red blood cells in the urine.
The test for anti-glomerular basement membrane antibody (GBM), which is positive in Goodpasture's syndrome, is negative.
Cause
This condition, the clinical picture of which may include many features of systemic lupus erythematosis, has been reported. While the mechanism of disease has yet to be fully elucidated, the leading hypothesis is that the process is begun with an autoimmune process of unknown etiology that triggers production of ANCA. These antibodies will circulate at low levels until a pro-inflammatory trigger - such as infection, malignancy, or drug therapy. The trigger upregulates production of ANCA. Then, the large number of antibodies make it more likely that they will bind a neutrophil. Once bound, the neutrophil degranulates. The degranulation releases toxins that cause endothelial injury, that is, damage to vessels of glomeruli.[3]
Treatment
The customary treatment involves long term dosage of prednisone, alternated or combined with cytotoxic drugs, such as cyclophosphamide or azathioprine.
Plasmapheresis may also be indicated in the acute setting to remove ANCA antibodies.
Rituximab has been investigated.[4]
See also
References
- ^ Nagai Y, Hasegawa M, Igarashi N, Tanaka S, Yamanaka M, Ishikawa O (December 2008). "Cutaneous manifestations and histological features of microscopic polyangiitis". Eur J Dermatol. doi:. PMID 19059827. http://www.john-libbey-eurotext.fr/medline.md?issn=1167-1122&vol=&iss=&page=.
- ^ Seishima M, Oyama Z, Oda M (2004). "Skin eruptions associated with microscopic polyangiitis". Eur J Dermatol 14 (4): 255–8. PMID 15319159. http://www.john-libbey-eurotext.fr/medline.md?issn=1167-1122&vol=14&iss=4&page=255.
- ^ Xiao H, Heeringa P, Hu P, et al. (October 2002). "Antineutrophil cytoplasmic autoantibodies specific for myeloperoxidase cause glomerulonephritis and vasculitis in mice". J. Clin. Invest. 110 (7): 955–63. doi:. PMID 12370273. PMC 151154. http://dx.doi.org/10.1172/JCI15918.
- ^ Jayne D (January 2008). "Challenges in the management of microscopic polyangiitis: past, present and future". Curr Opin Rheumatol 20 (1): 3–9. doi:. PMID 18281850. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00002281-200801000-00003.
External links
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