VALUE OF DNA ANALYSIS IN ADDITION TO CYTOLOGICAL TESTING IN THE DIAGNOSIS OF MALIGNANT PLEURAL EFFUSIONS

Background - Aneuploidy appears to be a highly specific marker for can cer, and measurement of cellular DNA content by flow cytometry is rapi d and reliable. This study was undertaken to determine if the addition of DNA analysis improved the sensitivity of cytological diagnosis of malignancy in pleural fluid. Methods - Pleural effusions from 92 patie nts were studied by cytological examination and flow cytometry. Result s - In 41 patients the final diagnosis was malignancy, there were 40 c ases of benign effusions including 22 with pleural tuberculosis, and i n the remaining 11 patients with biopsy proven cancer the presence of malignant cells was not found by cytological and histological means in the pleural fluid. Aneuploidy and cytological malignancy were found i n 14 samples. There were seven cases with abnormal flow cytometry and negative cytological results. In 12 patients the cytological test resu lts were positive but DNA analysis was normal. Thirty six samples of f luid were both diploid and cytologically negative. Of the 22 tuberculo us effusions seven contained aneuploid cells. The sensitivity of DNA a nd cytological analysis was 51.2% and 63.4%, respectively. The specifi city of DNA analysis was 74.5%. Conclusions - DNA analysis of cells in malignant pleural effusions is both less sensitive and specific than the cytological diagnosis. Flow cytometric analysis is not recommended for routine use in the diagnosis of pleural effusions.