Abstract
Pulmonary protozoal infections are rare. A 28-year-old woman was admitted to hospital with chief complains of cough, sputum, and dyspnea. The clinical laboratory tests for blood revealed an increased eosinophil percentage of 31.3% and significantly elevated total IgE. The chest computed tomography scan revealed that bilateral bronchial walls were thickening, accompanied with patchy spots scattered throughout bilateral lungs. A suspected multiflagellated protozoan was observed under a light microscope. But some different features were observed by electron microscopy, such as the orientation of flagella and nucleus. Besides, both bronchoalveolar lavage fluid and bronchoscopic brush smears underwent Gram staining and Pap staining, which revealed that numerous respiratory ciliated cells were scattered or accumulated in the sample. Finally, she was diagnosed with eosinophil pneumonia. Metronidazole, bronchodilators, and mucolytics were taken for 5 d and symptoms and pulmonary ventilation function improved. We herein report a case of chronic eosinophilic pneumonia, which was misdiagnosed as multiflagellated protozoan infection, and it is suggested that reliable diagnosis approaches are necessary, rather than clinical symptoms and morphological features.