DNA HISTOGRAM TYPING IN A SERIES OF 707 TUMORS OF THE CENTRAL AND PERIPHERAL NERVOUS-SYSTEM

The diagnostic value of ploidy level was investigated in a series of 7 07 tumors (from 707 patients) of the central and peripheral nervous sy stem. The series contained 91 nerve sheath tumors (NSTs), 222 meningio mas (MNGs), 37 primitive neuroectodermal tumors (PNETs), 293 glial tum ors of the adult (ATTs), and 64 brain metastases (MTTs). The ploidy le vel of each tumor was obtained by means of its DNA histogram type (DHT ), which was computed (digital cell image analysis) on Feulgen-stained nuclei from archival formalin-fixed paraffin-embedded materials. The data reveal that the measurement of the ploidy level showed a diagnost ic value in some of these tumor cases. Indeed, the proportion of highl y aneuploid cases significantly (p < 0.05-0.01) decreased according to the sequence PNETs (72%) --> MTTs (64%) --> ATTs (40%) --> NSTs (23%) --> MNGs (9%). Nevertheless, this significant diagnostic value in ter ms of a distinction between benignity and malignancy only appears when all the tumors are taken into consideration. Indeed, at the level of one individual patient, our study shows that, like traumatic neuromas, schwannomas, or classical meningiomas, completely benign tumors can e xhibit a high aneuploidy level. In contrast, some tumors from histopat hological groups like brain metastases or PNETs, which are known to be clinically aggressive, could be completely diploid.