Evaluation of AgNOR count in distinguishing benign from malignant mesothelial cells in pleural fluids

The authors have evaluated in eight reactive and eight malignant pleural effusions the number of intranuclear dots representing the nucleolar associated proteins stained with silver colloid technique (interphase nucleolar organizer regions-AgNORs). The mean number per nucleus in benign reactive effusions was 1.56 (SD 0.77) while in mesotheliomatous effusions it was 2.81 (SD 1.44). The statistical analysis of values, by Mann-Whitney U Wilcoxon Rank Sum W Test, revealed a significant difference of AgNOR counts in the two cytological samples. The variability of AgNOR areas and morphologies in reactive and mesotheliomatous nuclei in pleural fluids is evaluated applying automatic image analysis.