[Case report and review of literature on seasonal distribution and pathogenesis of acute eosinophilic pneumonia in Japan].

A 49-year-old female was admitted because of high grade fever and dyspnea. Chest roentgenogram revealed diffuse reticulo-linear shadows. Laboratory findings showed peripheral blood eosinophilia, and blood gas analysis demonstrated severe hypoxemia. A few days after admission, her symptoms and signs improved, and the abnormal shadows on the chest roentgenograms decreased without treatment. To determine the diagnosis and evaluate the pathological findings and pathogenesis, we performed open lung biopsy. Bronchoalveolar lavage at the operation revealed increased total cell count and increased markedly, number of eosinophils, and the open lung biopsy specimen showed acute interstitial pneumonia with eosinophilic infiltration. We performed a study of precipitating antibodies against fourteen kinds of fungi and environmental provocation tests, with all results being negative. We diagnosed this case as having acute eosinophilic pneumonia clinicopathologically (Allen, 1989). We reviewed 22 cases with acute eosinophilic pneumonia previously reported in Japan including our case. These 22 cases demonstrated a seasonal tendency of onset in spring and summer. Eleven of 22 cases were tested for precipitating antibodies to several fungi, 3 of which showed positive results against Trichosporon cutaneum, Trichoderma viride and Aspergillus species. The clinical features of acute eosinophilic pneumonia resemble those of summer type hypersensitivity pneumonitis. Therefore, it is important to diagnose AEP on the basis of clinical symptoms, and precipitating antibody, viral titer and pathological findings.