title: Cytologically proved malignant pleural effusions: distribution of transudates and exudates.
abstract: OBJECTIVE
  This study attempts to determine the distribution of transudates vs exudates in pathologically proved malignant pleural effusions and the necessity for cytologic studies in patients with a transudative effusion.
  
  
  METHODS
  A retrospective review of all cytologically positive malignant pleural effusions was performed at Duke University Medical Center over an 18-month period. All effusions were characterized as a transudate or an exudate based on standard criteria, including lactate dehydrogenase and protein values.
  
  
  RESULTS
  Ninety-eight patients with a mean age of 62 years were identified as having a cytologically positive malignant pleural effusion and blood chemistry values available to distinguish an exudate from transudate. Ninety-seven patients (99%, 95% confidence interval; 0.94 to 0.99) had criteria for an exudative effusion. One patient (1%) with diffuse metastatic lung cancer had a borderline transudate and was in congestive heart failure at the time of thoracentesis.
  
  
  CONCLUSIONS
  Cytologically positive pleural effusions for malignancy are almost always exudates. Cytologic evaluation for malignant cells of a transudative pleural effusion is not recommended.
authors.affiliation: Department of Internal Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Assi
authors.forename: J L
authors.initials: JL
authors.lastname: Caruso
authors.forename: J
authors.initials: J
authors.lastname: Herndon
authors.forename: E F
authors.initials: EF
authors.lastname: Patz
mesh_terms: D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000166:cytology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016066:Pleural Effusion, Malignant / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D012189:Retrospective Studies