[MPO-ANCA positive two cases associated with interstitial pneumonitis].

We describe two cases (61-year-old female and 71-year-old male) with MPO-ANCA (myeloperoxidase-antineutrophil cytoplasmic antibody) positive who developed severe interstitial pneumonitis. They presented at our hospital with dyspnea and dry cough. The hypoxia and abnormal shadow on chest X-ray led to a diagnosis of interstitial pneumonitis. Serologic studies revealed the high titers of MPO-ANCA in two cases. They were treated with methylprednisolone, immunosuppressant agents and plasma exchange. The pneumonitis and the titers of MPO-ANCA improved on these therapies, The former was introduced continuous hemodialysis therapy and the later continued nephrotic syndrome. These renal damages did not recover, regardless of the reduction of the titers of MPO-ANCA. It is concluded that methylprednisolone pulse therapy, immunosuppressant agents and plasma exchange therapy are useful to interstitial pneumonitis in patient with positive of MPO-ANCA. The measurement of MPO-ANCA is useful to interstitial pneumonitis in patient with positive of MPO-ANCA. The measurement of MPO-ANCA is useful maker of interstitial pneumonitis for unknown causes.