[A case of early-onset cyclophosphamide-induced pneumonitis diagnosed by rechallenge test]

A 59-year-old woman began to complain of cough, dyspnea, and fever 2 weeks after 3 courses of chemotherapy with cyclophosphamide (800 mg) and adriamycin (80 mg) for breast cancer. Chest radiography showed diffuse ground-glass shadows in the central areas of bilateral lung fields. Chest CT also showed diffuse ground-glass opacities in the central areas of bilateral lung fields. Arterial blood gas analysis revealed mild hypoxia. A lymphocyte stimulation test with peripheral blood lymphocytes for cyclophosphamide was negative. A mild increase of lymphocytes was observed in the cell population of bronchoalveolar lavage fluids and no microorganisms were detected. Her respiratory condition improved after glucocorticoid therapy. A rechallenge test with cyclophosphamide was performed after obtaining informed consent. There was no significant change in symptoms or chest radiography results 24 hours after intravenous administration of cyclophosphamide (100 mg). However, a transient decrease of PaO2 with peripheral eosinophilia was observed. Thus, a diagnosis of early-onset cyclophosphamide-induced pneumonitis was established.