[A case of interstitial pneumonia of polymyositis-dermatomyositis with various pathological findings in open lung biopsy].

A 60-year-old woman was admitted to our hospital with a two month history of dry cough and dyspnea on exertion. A chest roentgenogram revealed diffuse interstitial shadows with a reduction of lower lung volume. Laboratory examinations revealed an increase in CPK and aldolase. There was decreased proximal muscle power, and the findings of a biopsy of the right deltoid were compatible with polymyositis. Myositic symptoms were stable, but the respiratory symptoms worsened, and an open lung biopsy was performed for diagnosis and to determine the best treatment. The histological findings of biopsy materials demonstrated active interstitial pneumonia complicated by cellular interstitial pneumonia, bronchiolitis obliterans organizing pneumonia, usual interstitial pneumonia and lymphoid hyperplasia. The patient responded well to adrenocorticosteroid and immunosuppressive therapy, and is now attending as an out patient. It is well known that PM-DM can be associated with interstitial pneumonia, and this complication is an important prognostic factor clinically. The pathological patterns of interstitial pneumonia in PM-DM may be divided into usual interstitial pneumonia and bronchiolitis obliterans organizing pneumonia. Furthermore, it is well documented that these patterns are concurrent with the response to adrenocorticosteroid and prognostic factors. However, our case of PM-DM, in which various patterns such as rheumatoid arthritis (RA) were pathologically revealed, cannot be considered as having uniform pathological pattern. We consider that pulmonary pathological patterns of PM-DM are very varied, as with RA. It is a very important to evaluate the nature of these patterns and the subsequent clinical course in PM-DM with interstitial pneumonia.