Acute Eosinophilic Pneumonia as a Rare Cause of Acute Onset Respiratory Failure

Acute eosinophilic pneumonia (AEP) is a rare but lifethreatening pulmonary disease characterized by the acute onset of respiratory symptoms, hypoxemia, and diffuse pulmonary infiltrates.Its clinical presentation is often mistaken for pneumonia or acute respiratory distress syndrome, leading to diagnostic delay.We report the case of a 59-year-old female who presented with a 3-week history of dyspnea and cough and was initially treated with antibiotics for presumed pneumonia.During follow-up, progressive peripheral eosinophilia, eosinophils in bronchoalveolar lavage, histopathological findings, and radiological progression supported the diagnosis of AEP.Spirometry performed before discharge demonstrated an obstructive pattern with significant bronchodilator reversibility; however, clinical and physical findings did not support asthma.Subsequently, the reversible obstruction was attributed to transient airway inflammation associated with AEP.Methylprednisolone (1 mg/kg) was initiated, resulting in rapid and dramatic clinical improvement.This case highlights the importance of considering AEP in the differential diagnosis of antibioticrefractory pneumonia, the diagnostic value of spirometry findings, and the effectiveness of corticosteroid therapy.