Acute eosinophilic pneumonia as a reversible cause of noninfectious respiratory failure.

Although chronic eosinophilic pneumonia is a well-known disorder, acute eosinophilic pneumonia has not been as well characterized. We describe the clinical features, results of bronchoalveolar lavage, and follow-up studies of four patients with acute eosinophilic pneumonia. The patients presented with an acute febrile illness, severe hypoxemia (partial pressure of arterial oxygen less than 60 mm Hg), diffuse pulmonary infiltrates, an increased number of eosinophils (mean +/- SEM, 42 +/- 4.8 percent) in bronchoalveolar-lavage fluid, and an absence of infection and previous atopic illness. The illness resolved rapidly after treatment with erythromycin and corticosteroids. The patients received doses of oral prednisone that were tapered over 10 days to 12 weeks, and none have relapsed since the steroids were discontinued. After a minimum follow-up period of five months, clinical evaluation, chest radiography, and pulmonary-function tests have shown no residual abnormalities attributable to the acute eosinophilic pneumonia. Follow-up bronchoalveolar lavage has demonstrated less than or equal to 1 percent eosinophils in all patients. We believe that we are describing an acute form of eosinophilic lung disease distinct from previously described syndromes. It can be diagnosed by bronchoalveolar lavage and seems to respond to treatment with corticosteroids.