Abstract
Recently, we experienced a 42-year-old female case of M. pneumoniae pneumonia with eosinophilic pleural effusion. The mechanism of eosinophilic pleural effusion was examined. After digestive trouble, fever (39.0°C), cough and right back pain developed. Chest roentgenograms revealed an air space in the right lower lung field, right hilar lymphoadenopathy, and right pleural effusion. In serum the M. pneumoniae CF titer increased to 1:512, and the PHA titer to 1:20480. In the pleural fluid, the M. pneumoniae CF titer increased to 1:1024, and the PHA titer to 1:20480. Although M. pneumoniae was not isolated from the throat swab specimen or pleural fluid, on the basis of these results, a diagnosis of M. pneumoniae infection was urade. The pleural fluid was exudative (yellowish in color, specific gravity 1.041, protein 5.8g/dl, Rivalta reaction (+)). Papanicolau's stain revealed many eosinophils in the pleural fluid (eosinophils 57%, neutrophils 3%, lymphocytes 40%), and in the peripheral blood, eosinophilia (27%) and elevated Ig-E level were demonstrated. Pleural effusion accompanying M. pneumoniae pneumonia is rare in adults, and its mechanism is not clear. In addition, no eosinophilic pleural effusion due to M. pneumoniae pneumonia has ever been reported, this being the first reported case in the literature. In this case, because of many eosinophils in the pleural fluid, eosinophilia and elevated Ig-E level in the peripheral blood, it was suggested that the mechanism of eosinophilic pleural effusion was that known as immediate type allergy.
