[Microscopic polyangiitis as etiology for lung fibrosis--a known but often late-diagnosed cause].

Background And Purpose: Lung fibrosis as first symptomatic manifestation of microscopic polyangiitis (MPA) is rare. It is characterized by progressive exertional dyspnea, radiologic detection of reticular shadowing, and increased titers of MPA-associated autoantibodies. This case study shall remind of the rare treatable cause of lung fibrosis.