Methotrexate-Induced Hypersensitivity Pneumonitis in a Patient with Rheumatoid Arthritis-A Case Report

Abstract

Hypersensitivity pneumonitis is caused by exposure to a variety of agents. Differentiating hypersensitivity pneumonitis from other interstitial lung diseases is not easy. The diagnosis relies on a combination of exposure history, symptoms, radiological findings, and pathological characteristics. Once this diagnosis is made, corticosteroids should be administered as soon as possible, and exposure to the causative agent avoided. We report a 59-year-old woman with rheumatoid arthritis for 4 years, who was treated with several medications including methotrexate. She was admitted to our hospital with pneumonia, presenting with fever, chills, dry cough, and general malaise. Subsequently, she had increasing dyspnea, hypoxemia, and progressive diffuse interstitial pneumonia and fever, which persisted despite antibiotics treatment. Because she was taking methotrexate, methotrexate-induced pneumonitis was strongly suspected, and was later diagnosed after a series of studies. The patient improved dramatically after the steroid treatment, and she was discharged with complete resolution of the hypersensitivity pneumonitis. Methotrexate pneumonitis should be considered in patients treated with the drug and presenting with interstitial pneumonia.