Image analysis and flow cytometric DNA studies of benign and malignant body cavity fluids: Reappraisal of the role of current methods in the differential diagnosis of reactive versus malignant conditions

Cytologic examination of body fluids is commonly performed in the clinical laboratory. Determination of the presence of malignancy may sometimes be di fficult. In this study, we prospectively studied 60 body fluids with a pane l of antibodies, including MOC-31, epithelial membrane antigen, carcinoembr yonic antigen, B72.3, keratin, desmin, and CA-125. DNA and S-phase studies were performed both by now cytometry and image analysis. Thirty-seven fluid s were classified as benign and 23 were classified as malignant. The sensit ivity of the antibodies for identification of carcinoma in descending order of percentage detection rate were MOC-31 (95%), epithelial membrane antige n (93%), B72.3 (84%), and carcinoembryonic antigen (80%). Desmin stained me sothelial cells in all cases. CA-125 gave similar results but was less spec ific. Flow cytometry detected 14 of 20 malignant fluids and image analysis 17 of 23 by identifying an aneuploid population. Benign reactive mesothelia l cells were not aneuploid. Tetraploidy due to reactive mesothelial cells w as found in 9 of 37 body fluids. Their S-phase fraction was low (average, 3 .2%). Tetraploidy in malignant cells was distinguished from the reactive me sothelial cells by high S-phase (average, 25.95). S-phase had some use as a discriminating factor, because no benign reactive cases had more than 17%. However, 7 of 23 malignant cases had a value below 17%. DNA analysis by im age was more sensitive the and specific than now. Either may be used when i mmunocytochemistry is nondiagnostic or cannot be performed.