Role of DNA flow cytometry and immunocytochemical analysis in diagnosis of malignant effusions.

Body cavity fluid examination sometimes presents a diagnostic challenge in cytology practice. This study was undertaken to evaluate efficacy of cytomorphology, epithelial membrane antigen immunocytochemistry (EMA-ICC) and DNA flow cytometry (FCM) in detection of malignant cells in effusions. One hundred effusions (55 pleural, 44 ascitic, and 1 pericardial fluid) were studied by cytology, EMA, and FCM. There were 29 malignant and 71 benign cases. On cytology, 28 of 29 malignant cases were diagnosed. With no false positives, the sensitivity and specificity was 96.55% and 100% respectively. FCM detected aneuploidy in 85.71% of cytologically malignant and 4.17% of cytologically benign effusions. EMA was positive in 75% of cytologically malignant and 4.17% of cytologically benign cases. EMA had lower sensitivity than cytology; 75.86% versus 96.55%. Sensitivity and specificity of FCM was 86.21%, and 97.18% respectively. FCM had lower sensitivity than cytology; 86.21% versus 96.55%. Sensitivity increased to 100% (P < 0.05) when the combinations of cytology plus EMA or cytology plus ploidy were applied compared to cytology alone (96.55%). Also, the combination of cytology plus EMA had higher sensitivity than EMA alone (100% versus 75.86%, P < 0.05) and combined cytology plus ploidy had higher sensitivity than ploidy alone (100% versus 86.21%, P < 0.05). The study demonstrates the usefulness of EMA-ICC and DNA FCM as adjuncts to cytology to diagnose malignancy in effusions. FCM in combination with ICC can be further developed to reduce number of false-negative cases on cytology and add objectivity to cytologically doubtful or equivocal cases.