Epithelioid pleural mesotheliomas and pulmonary adenocarcinomas: a comparative DNA flow cytometric study

The DNA flow cytometric characteristics of 23 immunohistochemically and ultrastructurally proven pleural epithelioid mesotheliomas were compared with those of 41 primary pulmonary adenocarcinomas. Multiple, separate tissue blocks were analyzed from each neoplasm to assess DNA heterogeneity. All of the pleural mesotheliomas and 80% of the pulmonary adenocarcinomas manifested a homogeneous DNA ploidy (DNA stability). A significant statistical difference in the ploidy pattern between pleural mesotheliomas and pulmonary adenocarcinomas was noted (P < .001). Mesotheliomas were mostly diploid (78%) and adenocarcinomas were preponderantly aneuploid (88%). The proliferative rate and DNA indexes of the aneuploid adenocarcinomas were significantly higher than those of pleural mesotheliomas (P < .001). There was no statistical significance between the proliferative rates of diploid mesotheliomas and those of adenocarcinomas. We conclude that the DNA flow cytometric characteristics of mesotheliomas are significantly different from those of pulmonary adenocarcinomas. The clinical implications of these findings are discussed.