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This small vessel vasculitis is also known as microscopic polyangiitis. It is a disease of middle aged males and mainly affects the kidneys, skin, and lungs. Like polyarteritis nodosa, the disease presents with constitutional symptoms of fever, malaise, myalgia, and weight loss. Skin lesions occur in 30-50% presenting with purpura and rarely nodules and ulcers.

One of the diagnostic hallmarks is the presence of antineutrophil cytoplasmic antibodies (p-ANCA). The kidney shows a focal and segmental glomerulonephritis. The skin shows a leukocytoclastic vasculitis. In nodular skin lesions, the vessels of the dermis and subcutaneous fat may be involved.


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SYNONYMS Microscopic polyangiitis
INCIDENCE 1:100,000
AGE RANGE-MEDIAN Mean 50 years
Male slight predominance


Laboratory Markers  
ANCA PR3 ANCA and MPO-ANCA are present in 40% and 50% of cases with 10% negative


Clinical and histopathologic features of 8 patients with microscopic polyangiitis including two with a slowly progressive clinical course.

Department of Dermatology, St Marianna University School of Medicine, Kanagawa, Japan.

J Am Acad Dermatol. 2007 Nov;57(5):840-8. Abstract quote

BACKGROUND: Microscopic polyangiitis (MPA) is a systemic antineutrophil cytoplasmic autoantibody-associated vasculitis associated with necrotizing and crescentic glomerulonephritis and pulmonary capillaritis. MPA generally has a rapidly progressive clinical course, but there have been recent reports of slowly progressive cases.

OBJECTIVE: To evaluate the typical cutaneous findings of MPA, we recorded the clinical and histopathologic features of the cutaneous manifestations.

METHODS: Eight patients with MPA, who had presented with cutaneous manifestations between 2001 and 2005 in our department, were retrospectively reviewed. They had necrotizing vasculitis in their cutaneous lesions as confirmed by skin biopsy specimens. Patients with other known connective tissue diseases were not included in the study.

RESULTS: All 8 patients with MPA presented cutaneously with erythematous macules on their extremities. Livedo reticularis (5/8, 68%) was also observed. Six of the 8 patients with MPA were given the diagnosis within 3 months of their initial manifestation. In skin biopsy specimens, necrotizing vasculitis was noted in the reticular dermis to the subcutaneous fat. In contrast, the other two patients with MPA were given the diagnosis about 10 years after their initial manifestation. Histopathologic findings demonstrated necrotizing vasculitis with moderate neutrophilic infiltrations in the papillary to middle dermis in the latter two patients. Serum myeloperoxidase-antineutrophil cytoplasmic autoantibody levels were only moderlately elevated in the latter two patients and they were given the diagnosis of slowly progressive MPA. Histopathologically, palisading granulomas were present on the elbow of one of them.

LIMITATIONS: The study was based on histopathological analysis in a limited number of patients due to the rareness of the investigated disease.

CONCLUSIONS: There appears to be a correlation between a slowly progressive clinical course of MPA and the depth of dermal involvement and the severity of neutrophilic infiltration in biopsy specimens. Based on these results, we believe that these characteristic patterns may help clinicians establish an earlier diagnosis of possible MPA with positive antineutrophil cytoplasmic autoantibody titers.
Pulmonary-Renal syndrome

Arch Intern Med 1996;156:440-445



General Segmental vascular necrosis with neutrophils and monocytes with leukocytoclasia and fibrinoid necrosis

Am J Clin Pathol 1995;104:7-16

Hemorrhagic alveolar capillaritis most common finding with increased neutrophils in alveolar capillaries with occasional leukocytoclasia

May have overt intra-alveolar hemorrhage




Long-term followup of polyarteritis nodosa, microscopic polyangiitis, and Churg-Strauss syndrome: analysis of four prospective trials including 278 patients.

Gayraud M, Guillevin L, le Toumelin P, Cohen P, Lhote F, Casassus P, Jarrousse B

French Vasculitis Study Group. H pital Avicenne, Bobigny, France.

Arthritis Rheum 2001 Mar;44(3):666-75 Abstract quote

OBJECTIVE: To determine the long-term outcome of patients with polyarteritis nodosa (PAN), microscopic polyangiitis (MPA), and Churg-Strauss syndrome (CSS), to compare the long-term outcome with the overall French population, to evaluate the impact on outcome of the type of vasculitis, prognostic factors, and treatments administered at diagnosis, and to analyze treatment side effects and sequelae.

METHODS: Data from PAN, MPA, and CSS patients (n = 278) who were enrolled between 1980 and 1993 were collected in 1996 and 1997 and analyzed. Two prognostic scoring systems, the Five-Factors Score (FFS) and the Birmingham Vasculitis Activity Score (BVAS), were used to evaluate all patients at the time of diagnosis.

RESULTS: The mean (+/- SD) followup of the entire population was 88.3 +/- 51.9 months (range 3 days to 192 months). Of the 85 deaths recorded, at least 41 were due to progressive vasculitis or its consequences. Death rates reflected disease severity, as assessed by the FFS (P = 0.004) and the BVAS (P < 0.0002), and the 2 scores were correlated (r = 0.69). Relapses, rarer in hepatitis B virus (HBV)-related PAN (7.9%) than in MPA (34.5%) (P = 0.004), occurred in 56 patients (20.1%) and did not reflect disease severity. Survival curves were similar for the subpopulation of 215 patients with CSS, MPA, and non-HBV-related PAN who were given first-line corticosteroids (CS) with or without cyclophosphamide (CYC). However, CS with CYC therapy significantly prolonged survival for patients with FFS scores > or =2 (P = 0.041). Relapse rates were similar regardless of the treatment regimen; only patients treated with CS alone had uncontrolled disease. CYC was associated with a greater frequency of side effects (P < 0.00001).

CONCLUSION: Rates of mortality due to PAN (related or unrelated to HBV), MPA, and CSS reflected disease severity and were higher than the mortality rate in the general population (P < 0.0004). Rates of relapse, more common in MPA than HBV-related PAN patients, did not reflect disease severity. Survival rates were better among the more severely ill patients who had received first-line CYC. Based on these findings, we recommend that the intensity of the initial treatment be consistent with the severity of the disease. The use of the FFS and BVAS scores improved the ability to evaluate the therapeutic response.

TREATMENT Corticosteroids and cyclophosphamide
Beneficial effect of gabexate mesilate on microscopic polyangiitis with renal dysfunction and pulmonary hemorrhage: A case report.

Department of Cardiology, Kyoto Prefectural Rakuto Hospital, Japan.


Angiology. 2006 Aug-Sep;57(4):522-5. Abstract quote

Corticosteroids and cyclophosphamide are the mainstay of the treatment of microscopic polyangiitis involving pulmonary hemorrhage or rapidly progressive glomerulonephritis. However, patients with advanced age are unable to tolerate this combined therapy, because of a relatively high incidence of side effects including infection, hemorrhagic cystitis, and bone marrow suppression.

The authors encountered an 80-year-old patient with pulmonary hemorrhage and renal dysfunction ascribed to microscopic polyangiitis and achieved successful treatment by employing gabexate mesilate in addition to corticosteroids.

The present case suggests that gabexate mesilate may be a therapeutic option for microscopic polyangiitis with progressive renal failure and pulmonary hemorrhage.

Semin Diagn Pathol 2001;18:3-13.
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Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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Last Updated November 16, 2007

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