[Fulminant interstitial pneumonia associated with polyarteritis nodosa]

A 54-year-old man was referred to our hospital because of fever, abdominal pain, hematemesis, and dyspnea on exertion. Laboratory examination on admission revealed elevations of WBC count and CRP. a low serum complement level, hypoxemia, and microhematuria. A chest X-ray film and a CT scan showed bilateral interstitial pneumonia and cardiomegaly. Angiography showed microaneurysms in peripheral branches of the superior mesenteric artery, the hepatic artery, and the right renal artery. Examination of a specimen of the right quadriceps muscle revealed arteritis with fibrinoid necrosis in a small artery, which was consistent with polyarteritis nodosa (PN). A specimen obtained by transbronchial lung biopsy before treatment showed interstitial mononuclear cell infiltration and edema. PN with interstitial pneumonia was diagnosed and the patient was treated with 1 g of methylprednisolone for 3 days, followed by 60 mg of prednisolone and 100 mg of cyclophosphamide daily. The interstitial pneumonia progressed. Despite a second trial of steroid pulse therapy in addition to mechanical ventilation and various kinds of antibiotics, the patient died of respiratory failure on the 35th hospital day. A specimen obtained by transbronchial lung biopsy 3 days before death revealed proliferation of fibroblasts, mononuclear cell infiltration in the interstitium, and hyaline membrane formation in air spaces. No evidence of infection was found. Interstitial pneumonia associated with PN had been considered to be quite rare, but recently some cases resembling the present case have been reported. We believe that interstitial pneumonia associated with PN might not be rare, and the present case shows that it can be fulminant.