METHOTREXATE-INDUCED PNEUMONITIS IN PATIENTS WITH RHEUMATOID-ARTHRITIS AND PSORIATIC-ARTHRITIS - REPORT OF 5 CASES AND REVIEW OF THE LITERATURE

Pneumonitis is emerging as one of the most unpredictable and potential ly serious, adverse effects of treatment with MTX. Its prevalence in r heumatoid arthritis (RA) has been estimated from several retrospective and prospective studies to range from 0.3% to 18%, On the other hand, MTX-induced pneumonitis seems to be very rare in psoriatic arthritis (PsA). Our review of 194 RA patients and 38 PsA patients receiving MTX has identified four RA patients and one PsA patient with MTX-induced pneumonitis, giving a prevalence of 2.1% and 0.03%, respectively, Diag nosis was suggested by clinical history and radiographic findings, but the bronchoalveolar lavage plays an important role both in excluding infectious agents and in providing information for understanding the p athogenesis of lung injury, The presence of a lymphocyte alveolitis wi th a predominance of CD4+ T cells in 3 RA patients and CD8+ T cells wi th a concomitant increase in neutrophils in another case suggests that immunologically mediated reactions may be one damage mechanism in MTX -induced pneumonitis. Although risk factors for MTX-induced pulmonary toxicity are poorly understood, the presence in 3 out of 5 of our pati ents of pre-existing lung disease, represented by diffuse interstitial changes on chest X-ray, and mild bronchial asthma in two RA patients and by pulmonary silicosis in the patient with PsA may account for a p redisposition to the development of MTX pneumonitis.