RESUMO
Lung involvement in systemic disease may be a manifestation of the underlying pathological process, may be complication of the underlying disease or may be related to the treatment. Methotrexate [MTX], a folic acid antagonist is widely used in rheumatoid arthritis treatment; however, methotrexate-induced pulmonary drug toxicity occurs in 27% of patients. Difficulty in diagnosing these lesions had led-many researchers to assess the capability of every possible investigation [radiologic, functional, histopathologic, even 99mTc-DTPA scan] in reaching early diagnosis and differentiating it from those led by the original disease or that caused by infection, as early diagnosis and management carries good prognosis to an apparently fatal disease. Thus we compared in this study different diagnostic methods for detection of lung involvement due to MTX. We were able to detect pulmonary affection in some studies cases radiological and histopathologically, however, clinical and functional investigations lagged behind in their capabilieate the lung involvement.