title: What is the clinical significance of transudative malignant pleural effusion?
abstract: BACKGROUND
  A few reports of transudative malignant effusion on a small number of patients have suggested the need to perform routine cytologic examination in all cases of transudative pleural effusion, whether encountered for malignancy or not. The purpose of this study was to investigate whether cytologic examination should be performed in all cases of transudative pleural effusion for the diagnosis of malignancy.
  
  
  METHODS
  We performed a retrospective study of 229 consecutive patients with malignant pleural effusion, proven either cytologically or with biopsy. In patients with transudative pleural effusion, we reviewed medical records, results of transthoracic echocardiography, fiberoptic bronchoscopy, chest X-ray, chest CT scan, and ultrasonogram of the abdomen. These data were examined with particular attention to identifying whether or not the malignancy was suggested on chest X-ray, examining the involvement of the superior vena cava, great vessels, and lymph nodes, determining the presence of pericardial effusion, and observing the endobronchial obstruction.
  
  
  RESULTS
  Transudative malignant pleural effusion was observed in seven (3.1%) of the 229 patients, and was caused either by the malignancy itself (6 patients) or by coexisting cardiac diseases (1 patient). All the patients showed evidence suggesting the presence of malignancy at the time of initial thoracentesis, which facilitated the decision of most clinicians on whether to perform cytologic examination for the diagnosis of malignancy.
  
  
  CONCLUSIONS
  Therefore, in all cases of transudative pleaural effusion, no clinical implications indicating malignancy were found on cytologic examination.
authors.affiliation: Department of Internal Medicine, College of Medicine, Inha University, Incheon, Korea. jsryu@inha.ac.kr
authors.forename: Jeong-Seon
authors.initials: JS
authors.lastname: Ryu
authors.forename: Seong-Tae
authors.initials: ST
authors.lastname: Ryu
authors.forename: Young-Shin
authors.initials: YS
authors.lastname: Kim
authors.forename: Jae-Hwa
authors.initials: JH
authors.lastname: Cho
authors.forename: Hong-Lyeol
authors.initials: HL
authors.lastname: Lee
mesh_terms: D001706:Biopsy; D002277:Carcinoma / Q000145:classification / Q000473:pathology* / Q000556:secondary*; D005122:Exudates and Transudates; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging; D009382:Neoplasms, Unknown Primary / Q000473:pathology*; D016066:Pleural Effusion, Malignant / Q000378:metabolism / Q000473:pathology*; D012189:Retrospective Studies