Abstract

Methotrexate (MTX) is a folate antagonist used in several chronic inflammatory and neoplastic conditions. Pulmonary involvement is a rare adverse effect of MTX therapy and is particularly uncommon in psoriasis therapy. A 44-yearold male patient admitted to our hospital with shortness of breath, dry cough and fever. He was started on a MTX treatment 65 days ago and has taken 325mg cumulative dose of MTX. Chest-X-ray revealed diffuse bilateral interstitial infiltrates. Chest computed tomography (CT) scans demonstrated bilateral interstitial and alveolar infiltrates, peribroncho- vascular thickening and interlobular septal thickening. Pulmonary function studies revealed a restrictive ventilatory defect. After MTX treatment was discontinued, his symptoms rapidly resolved. Complete improvement was determined in pulmonary function tests and radiological changes on thoracic CT scan one month after the discontinuation of the MTX treatment. As interstitial pneumonitis is a potentially fatal but reversible complication, early respiratory symptoms even in patients on low-dose MTX treatment should be appropriately investigated.