Complete Atelectasis of Left Lung due to Methotrexate-associated Lymphoproliferative Disorder: A Case Report

A 59-year-old man who had been treated with methotrexate (MTX) for rheumatoid arthritis was referred to our hospital because of dyspnea. Chest computed tomography revealed a mass obstructing the left main bronchus and complete atelectasis of the left lung. Histopathology of the tumor obtained by trans-bronchial biopsies showed lymphoproliferative disorder (LPD) with positive results for Epstein-Barr virus-encoded small ribonucleic acid in situ hybridization. Withdrawal of MTX resulted in remission of both the tumor and atelectasis, supporting the diagnosis of MTX-associated LPD (MTX-LPD). We herein report a rare case of MTX-LPD with complete atelectasis of a unilateral lung.