[An autopsy case of MPO-ANCA-positive microscopic polyangiitis with manifestations of pulmonary hemorrhage and diffuse alveolar damage].

: A 68-year-old woman was admitted to our hospital because of fever of unknown origin and pain in the lower extremities. Six weeks after onset, diffuse infiltrative shadows were observed on chest X-ray films, and marked hypoxemia and progressive renal dysfunction suddenly developed. Corticosteroid therapy (2 courses of pulse therapy, each consisting of methylprednisolone at 500 mg/day for 3 days) was not effective, and the patient died 9 weeks after onset because of respiratory failure. Serologic tests were positive for MPO-ANCA. Histopathologic findings at autopsy disclosed arteriolar fibrinoid necrosis in tissues of the liver, spleen, lungs, and kidneys, thus yielding a diagnosis of microscopic polyangiitis. Lung specimens also demonstrated massive alveolar hemorrhaging in the mid-lung fields and diffuse alveolar damage (DAD) in all lobes. Pulmonary hemorrhage coexistent with DAD worsens the prognosis for microscopic polyangiitis in patients positive for MPO-ANCA.