Abstract
Pemetrexed is an antifolate chemotherapy agent that is active in malignant mesothelioma and non-small cell lung cancer (NSCLC). Pneumonitis is a rare side effect of Pemetrexed. We report the case of 72-year-old female with metastatic poorly differentiated lung adenocarcinoma. She was placed on maintenance pemetrexed and developed gradual progressive dyspnea after first cycle of maintenance of pemextrexed. The computed tomography (CT) of the chest showed ground glass opacity in both lung fields. Transbronchial lung biopsy showed uniform interstitial widening by a cellular chronic infiltrate with areas of type II pneumocyte and exudation of pale eosinophilic edema fluid; features consistent with acute lung injury. Patient improved both clinically and radiological after stopping pemetrexed and starting prednisone. Although pemetrexed induced lung injury is relatively rare, with the increasing use of peme-trexed in first-line treatment and in maintenance therapy of non-small cell lung cancer, awareness of this potential adverse effects is important.