Characterization of Pleural Effusions by Flow-cytometric DNA Analysis

Pleural effusions from 58 patients were studied by cytology and flow-cytometry. Relative cellular DNA content was measured, giving an estimate of ploidy as well as cell cycle distribution. Twenty-one patients had non-malignant diseases while the rest had malignant diseases. Pleural effusions from 13 patients contained malignant cells. In 2 cytologically equivocal cases and in one cytologically negative case aneuploid cells were demonstrated in the histograms. The cell cycle distribution of the diploid tumour cells did not differ from that of the diploid cells in benign effusions. The demonstration of an aneuploid histogram by flow cytometry favours a cancer diagnosis, and can provide valuable and decisive information in addition to cytological results.