Acute Eosinophilic Pneumonia Triggered by Carbamazepine Therapy: A Clinical and Radiologic Case Report

Acute eosinophilic pneumonia (AEP) is a type of interstitial lung disease characterized by eosinophilic infiltration of the lung parenchyma and can present as acute hypoxemic respiratory failure. Certain medications, including carbamazepine, have been rarely implicated in eosinophilic pulmonary syndromes and delayed systemic hypersensitivity reactions with pulmonary involvement. In this case, we report a 50-year-old man who developed acute eosinophilic pneumonia (AEP) characterized by diffuse bilateral pulmonary infiltrates with small pleural effusions on imaging following the initiation of carbamazepine therapy for epilepsy approximately four weeks prior to presentation. The patient presented with fever, dyspnea, and hypoxia. Imaging demonstrated bilateral infiltrates with mediastinal and hilar lymphadenopathy. Physical examination throughout hospitalization did not reveal any rash, edema, skin desquamation, or mucosal involvement despite concern for a drug-related hypersensitivity reaction. His clinical status worsened, leading to respiratory failure requiring intubation. Bronchoalveolar lavage (BAL) demonstrated significant eosinophilia (>25%), which was a key diagnostic finding supporting AEP. Although the patient did not meet full diagnostic criteria for DRESS syndrome, the timing of presentation and associated systemic findings raised concern for a broader carbamazepine-induced hypersensitivity reaction with predominant pulmonary involvement. This case highlights the importance of early recognition of carbamazepine-associated eosinophilic lung disease, particularly in patients with BAL eosinophilia and compatible radiologic findings, while also emphasizing the need to evaluate for possible multiorgan involvement in suspected drug-induced AEP.