(1131) Eosinophilic Enigma: An Uncommon Case of Acute Respiratory Illness

Introduction: Acute respiratory illnesses often present with a broad spectrum of symptoms making differential diagnosis challenging. Idiopathic acute eosinophilic pneumonia (IAEP) is a rare noninfectious condition characterized by an abrupt onset of respiratory symptoms, bilateral pulmonary infiltrates, and a predominance of eosinophils in the lung tissue and bronchoalveolar lavage (BAL) fluid. We present a case of IAEP in a 72-year-old female.

Description: A 72-year-old former smoker female, presented with worsening shortness of breath and nonproductive cough for 2 days. She required Bi-level Positive Airway Pressure due to hypoxia. Workup revealed mild leukocytosis with elevated neutrophil and eosinophil levels. Chest X-ray showed bilateral patchy airspace disease. Vasculitis, connective tissue disease panel, fungal studies, Influenza, and COVID-19 tests were negative. She was initially treated for suspected community-acquired pneumonia and decompensated heart failure with diuretics and antibiotics, but her condition worsened requiring intubation. BAL confirmed acute eosinophilic pneumonia (72% eosinophils). She was treated with steroids, leading to improvement, and the patient was successfully weaned off the ventilator.

Discussion: Acute eosinophilic pneumonia (AEP) is an uncommon condition with various potential causes, including infections, drug hypersensitivity, inhaled agents, and systemic idiopathic eosinophilic disorders. Although smoking habits have been associated with the onset of IAEP, no identifiable exposure or changes were observed in our patient. The clinical presentation is nonspecific and may overlap with other respiratory conditions, leading to delays in diagnosis. The absence of antibiotic response should raise suspicion for IAEP, warranting further investigation. White blood cell count at presentation usually shows increased leukocytosis with a predominance of neutrophils, while eosinophils are rarely elevated. Therefore, the gold standard for diagnosis is BAL. Glucocorticoids lead to rapid symptom improvement, but spontaneous recovery is possible. Clinicians must consider IAEP in cases of acute respiratory failure with diffuse interstitial pneumonia to avoid delayed diagnosis.