TRANSUDATIVE MALIGNANT PLEURAL EFFUSIONS - PREVALENCE AND MECHANISMS

Background, Malignant pleural effusions are classically exudative, tho ugh occasionally they can be transudative. We attempted to determine t he prevalence of transudative malignant pleural effusions and to descr ibe their clinical and radiographic characteristics. Methods, We studi ed the medical records of 215 patient with malignant pleural effusion, which contained complete data on pleural fluid analysis for 171 of th em. Results, Eight cases of transudative malignant effusion were found . Seven of these eight patients had a concomitant disorder known to ca use transudative pleural effusion. One patient had fluid overload due to renal failure, and another had been admitted earlier with congestiv e heart failure. Two patients had definite evidence of deep venous thr ombosis, allowing us to postulate pulmonary embolism as a factor contr ibuting to transudation. Three patients had CT evidence of superior ve na cava obstruction. Only one patient had no known associations with c auses of transudative effusion. Conclusion, Malignant pleural effusion s were transudative in 5% of our patients, In all except one patient, some evidence suggested the concomitant presence of a transudative sta te.