Microscopic polyangiitis (MPA) (synonyms: mPAN; ICD-10-GM M31.7 Microscopic polyangiitis) is a necrotizing (tissue dying) vasculitis (vascular inflammation) of small (“microscopic”) blood vessels, although larger vessels may also be affected. The inflammation of the blood vessels is triggered immunoreactively.
Microscopic polyangiitis belongs to the group of ANCA-associated vasculitides (AAV). ANCA stands for anti-neutrophil cytoplasmic antibodies. ANCA-associated vasculitides are systemic diseases, i.e. they can affect almost all organ systems. Microscopic polyangiitis is closely related to granulomatosis with polyangiitis (formerly Wegener’s granulomatosis). The main distinguishing criterion is the granuloma (nodule formation), which is not seen in microscopic polyangiitis. Symptoms of disease in the kidneys and lungs are typical of microscopic polyangiitis.
The disease is very rare.
The incidence (frequency of new cases) of microscopic polyangiitis is approximately 4 cases per 1,000,000 population per year.
Course and prognosis: The use of immunosuppressive therapy has significantly improved the life expectancy of affected individuals in recent years. With glucocorticoids and cyclophosphamide, long-term remission (disappearance of disease symptoms) can be achieved in 90% of cases.Recurrences are frequent, so patients should be monitored closely. Risk factors for relapse include early cessation of glucocorticoid therapy and lower total cyclophosphamide dose/duration of therapy.
