Acute Eosinophilic Pneumonia Leading to Acute Respiratory Failure in a Current Systemic Corticosteroid User
A 69-year-old female patient visited the emergency room with fever and dyspnea. She had been taking prednisolone (5 mg once per day) and methotrexate (2.5 mg once per week) for treatment of rheumatoid arthritis for 2 years. Five days prior to presentation, she developed cough and sputum, and experienced shortness of breath and fever the previous day. Upon arrival, her body temperature was 38.3℃. Plain chest X-ray and chest CT () showed peribronchial consolidation and ground-glass opacity in both lungs with interlobular septal thickening. Peripheral blood leukocyte count was 6,520/mm3 (neutrophils, 77.4%; eosinophils, 12.1%). High sensitivity CRP was 78.2 mg/L (normal; 0-1.0 mg/L) and Erythrocyte sedimentation rate (ESR) was 47 mm/hr (normal; 0-20 mm/hr). Arterial blood gas analysis on room air showed severe hypoxemia (pH 7.44, PaCO2 36.2 mmHg, PaO2 43.4 mmHg, and HCO3 24.7 mmol/L). After oxygen was supplied via a facial mask with a reservoir bag at 8 L/min, PaO2 increased to 76.4 mmHg. Based on suspected community-acquired pneumonia, she was admitted to hospital and intravenous levofloxacin was started. During the night, her dyspnea worsened and arterial oxygen tension dropped below 60 mmHg while on oxygen by facial mask with the reservoir bag at 10 L/min. Follow-up chest PA showed acutely increased opacity in both lungs (). Endotracheal intubation was performed and mechanical ventilation was started. Bronchoscopy was performed to identify etiological pathogens of pneumonia. Bronchoalveolar lavage (BAL) fluid showed a high proportion of eosinophils (eosinophils, 49%; lymphocytes, 35%; neutrophils, 16%). Culture of bronchial washing fluid did not show growth of any significant respiratory pathogens. Methylprednisolone was started (62.5 mg intravenously every 6 hours) with a diagnosis of AEP. Prone position ventilation was applied because hemoglobin saturation of arterial blood (SaO2) barely exceeded 90% while receiving 100% oxygen. Her condition improved dramatically after introduction of systemic corticosteroids and mechanical ventilation was discontinued on the fourth day. Chest PA taken on that day showed marked improvement of her previous lung infiltration (). The differential eosinophil count in the blood dropped to zero the day after commencement of intravenous corticosteroid therapy. She was almost fully recovered and discharged on hospital day 9.