The value of exfoliative cell cytology in the diagnosis of exudative pleural effusions

The sensitivity and specificity of exfoliative cell cytology for the diagnosis of exudative pleural effusions varies widely according to the etiologic causes. The aim of this study is to assess the diagnostic value of exfoliative cell cytology for the identification of exudative pleural effusions. This is a retrospective study of the patients with an exudative pleural effusion admitted at our clinic in the last twenty years. We have conducted the clinical, the cytological findings, and the diagnostic results of six hundred patients from hospital records.  Male to female ratio was 2.2:1 with a mean age of 42.8 years (range 18-78 years) among the patients. Samples were processed and evaluated according to the standard methods. Cytology results were reviewed and the patients were stratified according to the final diagnosis of their disease. Of the six hundred exudative effusions, 240 were malignant on exfoliative cytology pleural fluid alone. Adenocarcinoma was the most common type of malignancy. Tuberculosis was the second most frequent etiology for the exudative effusions followed by infection and collagen vascular diseases. Diagnostic accuracy of cytology showed a good correlation with the final diagnosis with an overall 70.1% sensitivity, 62.5% specificity, and a 95.9% positive predictive value for all exudative pleural effusions. Cytologic examination of the pleural fluid is a simple non-invasive procedure as the initial step for the diagnostic work up of patients with a pleural effusion.  Exfoliative cytology provides high a final diagnostic yield for the identification of an exudative pleural effusion etiology. Furthermore, cytologic analysis leads the clinician into the correct diagnostic pathway as the most informative laboratory tool even when it was not diagnostic by itself for equivocal cases.