Rheumatoid arthritis associated with methotrexate-induced pneumonitis: Improvement with i.v. cyclophosphamide therapy

Pneumonitis is one of the most serious adverse effects associated with low- dose weekly methotrexate (MTX) therapy. Immediate cessation of MTX, and the introduction of oxygen therapy and glucocorticoids usually results in a dr amatic improvement in the pulmonary toxicity. We report here a case of MTX- induced pneumonitis in a patient with rheumatoid arthritis (RA). Severe hyp oxemia and interstitial infiltration in both lung fields did not respond to the withdrawal of MTX and the administration of oxygen and steroid pulse t herapy. When intravenous cyclophosphamide (CYC) pulse therapy was initiated , however, rapid physiologic and radiographic improvement was seen. Our cas e suggests that CYC treatment may have a beneficial effect on MTX-induced p neumonitis that is resistant to steroid therapy.