COMPUTER-ASSISTED QUANTITATIVE DESCRIPTION OF CHROMATIN PATTERN AND DNA-PLOIDY LEVEL IN EPENDYMOMAS AND CHOROID-PLEXUS TUMORS

Computer-assisted microscope analyses of Feulgen-stained nuclei were u sed to quantitatively describe the chromatin pattern and to determine the DNA ploidy level in a series of 70 cases including 46 low-grade (b enign) ependymomas, 17 anaplastic (malignant) ependymomas, 3 choroid p lexus papillomas (benign) and 4 choroid plexus carcinomas (malignant). While the quantitative description of the chromatin pattern was carri ed out by means of 14 morphonuclear parameters relating to geometric, densitometric and textural features, the DNA ploidy level was assessed by means of DNA histogram typing. Of these 70 cases, proliferative ac tivity was assessed on 24, for which tissue was still available after the digital cell image analyses. This assessment was carried out by me ans of the determination of the immunohistochemical MIB-1 staining rel ating to the Ki-67 antigen. The results show that the determination of morphonuclear characteristics did not make it possible to distinguish between ependymal and choroid plexus tumours. Furthermore, neither th e computer-assisted microscope analyses of morphonuclear characteritic s nor the DNA ploidy level determination made it possible to distingui sh between low-grade and anaplastic ependymomas. In sharp contrast, th e determination of proliferative activity by means of the Ki-67 antige n immunohistochemical staining enabled such a distinction to be made.