Morphometric differences between cytologically benign and malignant serous effusions.

The morphometric differences between benign and malignant serous effusions, as diagnosed by standard cytologic criteria in 95 unselected cases (50 benign and 45 malignant), were studied using the IBAS semi-automated image analysis system, which calculates various parameters from tracings of cellular and nuclear outlines. Fourteen cases were also stained for cytokeratin proteins (with the CAM 5.2 antibody) by the immunoperoxidase technique and reanalyzed for positive cells. Significant differences were found for mean values between cytologically benign and malignant cases for cellular and nuclear areas, perimeters and maximum diameters, but not for two form factors. Some differences were enhanced in the CAM 5.2-stained cases. Real morphometric differences in samples of cells from benign and malignant cases are the basis of cytologic diagnosis. Fully automated diagnostic systems could operate on arbitrary threshold values, but there is considerable overlap in specimen means for all parameters between benign and malignant cases.