[Clinicopathological findings in 5 patients with acute eosinophilic pneumonia].

We studied 5 patients with acute eosinophilic pneumonia. Radiologic findings were Kerley's lines and pleural effusion on chest X-ray films, and interlobular septa on chest CT scans. Examination of transbronchial lung biopsy specimens revealed infiltration of eosinophils and lymphocytes into alveolar walls and edema of alveolar walls, interlobular septa, and perivascular connective tissue. The findings of interstitial edema were consistent with the radiological findings. Epithelial damage and bud-type intraluminal fibrosis were also seen, but residual alveolar structure was maintained. Bronchoalveolar lavage fluid contained abnormally high percentages of eosinophils and lympocytes. It also contained basophils and mast cells, which were not seen in fluid from normal subjects. Fluid from patients with chronic eosinophilic pneumonia had significantly fewer basophils than did fluid from those with acute eosinophilic pneumonia (p < 0.01). These findings suggest that release of chemical mediators from basophils plays a key role in interstitial edema in acute eosinophilic pneumonia.