Organization occurs in the interstitium and air spaces including airways, and a COP-like picture can be seen. The hallmark is the abundance of eosinophils among the lymphocytes, plasma cells, and scattered PMNs in the interstitium and mixed with alveolar macrophages in air spaces. Type II cell hyperplasia may be prominent. The diagnosis of acute eosinophilic pneumonia can be made by finding BAL fluid eosinophilia, as in case 6. These consist of diffuse, bilateral, alveolar, interstitial, or mixed opacities.
Some patients have spontaneous resolution.
Treatment with steroids can be begun when other possible diagnoses, especially infections, have been excluded. Response to steroids is rapid and without relapse. Also, he is older than other reported patients. Intrapleural blebs, as well as subpleural bullae, were noted in the resected lung tissue, but an eosinophilic pleuritis, often found in lung tissue resected for pneumothorax, was absent. The coagulation necrosis seen in the transbronchial biopsy of our patient probably signified pulmonary infarction related to smoking crack.