Fever and Cough in Methotrexate-treated Patients: An Approach.

The prevalence of acute methotrexate pneumonitis is up to 5.5%. Its presentation is often difficult to distinguish from opportunistic infections such as Pneumocystis carinii, nocardia, and cryptococcus or from interstitial infiltrates from the underlying rheumatic disease. Its recognition rests on the presence of cough, dyspnea, fever, new pulmonary function test abnormalities, and acute infiltrates on chest radiograph. The diagnosis ultimately rests on histologic confirmation and exclusion of infection. Bronchoalveolar lavage for cultures, and special staining of lavage and transbronchial histopathology specimens, often allows identification of opportunistic pathogens. Transbronchial biopsy may provide sufficient material for the diagnosis of either methotrexate pneumonitis of rheumatoid lung, particularly when correlated with the clinical presentation. Open lung biopsy should be considered if a diagnosis cannot be obtained on bronchoscopy. Despite a mortality of up to 10%, methotrexate pneumonitis usually responds to discontinuation of the drug and trial of corticosteroids.