Abstract
Microscopic polyarteritis (MPA) is a systemic necrotizing vasculitis affecting small blood vessels. Most of the cases initially respond to treatment with corticosteroids or cytotoxic agents, but relapse occurs frequently. Recently, we have experienced two cases of MPA accompanying pulmonary manifestations, one is pulmonary hemorrhage, the other is interstitial pneumonitis. Anti-neutrophil cytoplasmic antibody (ANCA) decreased in both cases following the intensive immunosuppressive therapy, however, they died of aggravation of the disease. Titer of plasma thrombomodulin and serum 7 S collagen remained high even after the intensive treatments suggesting that the endothelial damage and the destruction of the tissue basement membrane continued to be present. In addition, the association of interstitial pneumonitis is thought to be a rare but important pulmonary complication of MPA and also discussed with the literature.
