The clinical data of 4 patients with acute eosinophilic pneumonia (AEP) diagnosed in the Department of Respiratory and Critical Care Medicine, Peking University Third Hospital were retrospectively analyzed. All 4 patients were males, aged 28, 34, 43 and 68 years respectively. The main manifestations were fever, cough and dyspnea. Three cases had a history of smoking and 1 case had a history of ulcerative colitis. The proportion of eosinophils in bronchoalveolar lavage fluid (BALF) was 85%, 93%, 41% and 50%, respectively. The proportion of eosinophils in peripheral blood was 53.3% (16.29×10⁹/L), 25.1% (1.29×10⁹/L), 4.8% (0.4×10⁹/L) and 13.7% (1.55×10⁹/L), respectively. Blood gas analysis (without supplemental oxygen) showed type I respiratory failure in 1 case, hypoxemia in 3 cases. The total IgE (normal range ≤ 100.0 KU/L) in peripheral blood of the 4 cases was>2 500.0 KU/L, 60.3 KU/L, 379.4 KU/L and 407.0 KU/L, respectively. HRCT showed diffuse distribution of lesions in both lungs, including ground glass opacity, patchy consolidation and centrilobular nodules. After diagnosis, all patients were treated with systemic glucocorticoids. Fever, cough and dyspnea, as well as the chest CT lesions were significantly improved after treatment. The patients were followed up for 29 months, 16 months, 18 months and 24 months respectively, without recurrence. AEP is a rare disease which is easy to be misdiagnosed as severe pneumonia and/or ARDS. Eosinophilia in peripheral blood is suggestive of the disease, and timely BALF cell differentials is important for early diagnosis.

Pneumonia; Eosinophils; Bronchoalveolar lavage