Static DNA cytometry as a diagnostic aid in effusion cytology II.: DNA aneuploidy for identification of neoplastic cells in equivocal effusions

OBJECTIVE: The sensitivity of conventional cytology for identification of neoplastic cells in effusions is unsatisfactory, about 58%. The rate of diagnostically equivocal effusions in routine cytology is about 6%. DNA aneuploidy has previously been proven to be a sensitive and specific marker for the identification of tumor cells in effusions. In the present study we determined if malignancy can be identified in cytologically equivocal cells in effusions using DNA aneuploidy as a marker, thus decreasing the rate of cytologically equivocal diagnoses in effusions. STUDY DESIGN: One hundred cytologically equivocal effusions of the serous cavities were obtained from routine diagnostic material. Nuclear DNA content was measured after Feulgen staining using a TV image analysis system. Data were correlated with patient follow-up. RESULTS: DNA aneuploidy was assumed if abnormal DNA stemlines, a coefficient of variation of the first DNA stemline greater than or equal to 10% or cells >9c were observed. The sensitivity of DNA aneuploidy for the identification of malignancy was 55.9%. Specificity of DNA nonaneuploidy for benignity was 94.1%. The positive predictive value of the marker DNA aneuploidy for the occurrence of malignant cells was 97.9% since all but one DNA aneuploid case showed malignancy in follow-up. CONCLUSION: Image cytometry applying DNA aneuploidy as a parameter is able to detect the occurrence of malignant cells in cytologically equivocal effusions in about every second case. Thus, this method is able to increase diagnostic accuracy of conventional effusion cytology by decreasing the rate of diagnostically equivocal effusions.