CYTOLOGICALLY PROVED MALIGNANT PLEURAL EFFUSIONS - DISTRIBUTION OF TRANSUDATES AND EXUDATES

Purpose: This study attempts to determine the distribution of transuda tes vs exudates in pathologically proved malignant pleural effusions a nd the necessity for cytologic studies in patients with a transudative effusion, Materials and Methods: A retrospective review of all cytolo gically positive malignant pleural effusions was performed at Duke Uni versity Medical Center over an 18-month period. All effusions were cha racterized as a transudate or an exudate based on standard criteria, i ncluding lactate dehydrogenase and protein values. Results: Ninety-eig ht patients with a mean age of 62 years were identified as having a cy tologically positive malignant pleural effusion and blood chemistry va lues available to distinguish an exudate from transudate, Ninety-seven patients (99%, 95% confidence interval; 0.94 to 0.99) had criteria fo r an exudative effusion. One patient (1%) with diffuse metastatic lung cancer had a borderline transudate and was in congestive heart failur e at the time of thoracentesis. Conclusions: Cytologically positive pl eural effusions for malignancy are almost always exudates, Cytologic e valuation for malignant cells of a transudative pleural effusion is no t recommended.