Microscopic polyangiitis

Microscopic polyangiitis (MPA ) is a vasculitis (inflammation of blood vessels), which belongs to the group of autoimmune diseases. It is similar to Wegener 's granulomatosis ( Wegener's granulomatosis ), associated with ANCA autoantibodies.

Identification and Nomenclature

The MPA has been long regarded as a form of polyarteritis nodosa ( PAN). From this period stems nor the abbreviation " MPAN " to distinguish them from the classic PAN ( CPAN ) to distinguish. According to the Chapel Hill Consensus Conference of 1994, the MPA is to be considered as an independent disease.

Epidemiology

The MPA is a rare disease whose annual incidence is set to 4 cases per 1 million inhabitants.

Cause

An exact cause for the MPA is not known as in almost all autoimmune disease, a causal role of the pANCA autoantibody however discussed. In contrast to polyarteritis nodosa, the MPA is not associated with chronic hepatitis B.

Symptoms

  • Renal involvement (70 %): glomerulonephritis rapidly progressive glomerulonephritis to crescentic formation; Development of renal hypertension and renal insufficiency. In the urine, hematuria, proteinuria.
  • Lung: pulmonary vasculitis, possibly with alveolar hemorrhage and blood in the sputum, pneumonitis, fibrosing alveolitis rare.
  • Lesions (40 %): subcutaneous nodules, palpable purpura, especially in the lower extremities, possibly with necrosis, leukocytoclastic vasculitis.
  • Other symptoms: polyneuritis, sinusitis, episcleritis, myalgia, arthralgia, chronic bronchitis, double vision, bloody cold.

Differential Diagnosis

  • Tissue diseases, especially systemic lupus erythematosus
  • Polyarteritis nodosa
  • Other vasculitides

The MPA is clinically compare with Wegener's granulomatosis, histologically found but no granulomatous inflammation. Even with the MPA can be found ANCA ( antineutrophil cytoplasmic antibody) in 60% of cases these with the target antigen MPO ( myeloperoxidase ) are associated.

Therapy

There are no independent studies on the treatment of MPA. It is recommended adapted to the severity of therapy, as in Wegner 's granulomatosis. After an induction therapy - usually with corticosteroids and cyclophosphamide - is followed by a maintenance therapy - with azathioprine or methotrexate, the latter not with renal involvement.

Anti-neutrophil cytoplasmic antibody
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