Methotrexate pneumonitis in rheumatoid arthritis: potential risk factors. Four case reports and a review of the literature.

Methotrexate pneumonitis is emerging as one of the most unpredictable and potentially serious adverse effects associated with the use of low dose, pulse methotrexate in treating rheumatoid arthritis (RA). We report 4 new cases of methotrexate pneumonitis in patients with RA and review 6 published cases. A greater than expected proportion of patients had a smoking history, preexisting pulmonary disease and were male. Prognosis was better in those patients treated with corticosteroids.