[Lung diseases and treatment with methotrexate in rheumatoid arthritis].

Methotrexate (MTX) is used as sequential treatment of rheumatoid arthritis in doses ranging from 5 to 20 mg per week, but its effectiveness is impaired by undesirable and sometimes severe side-effects, notably on the lungs. We report three cases of lung disease in patients with rheumatoid arthritis under MTX therapy. Two patients had a lung infection caused by Escherichia coli and Pneumocystis carinii respectively and the third patient was a case of fatal pneumonia imputed to MTX. The signs and symptoms of these acute infectious or iatrogenic lung diseases are not specific. Bronchial endoscopy with bronchoalveolar lavage usually leads to a diagnostic of opportunistic infection, but it may also show an isolated excess, in both number and percentage, of alveolar leucocytes, pointing to a drug-induced pneumopathy. Acute respiratory failure due to MTX-induced pneumonia is not uncommon. It rapidly regresses either spontaneously or under corticosteroid therapy, but a number of deaths, as in our last patient, have been reported. The occurrence of these lung diseases is unrelated to the total dose of MTX. Reintroducing MTX does not mean that the condition will necessarily recur, but this can only be done in the absence of any other possible treatment.