DNA in chordomas of the clivus Blumenbachi.

Chordomas of the clivus are frequently denoted as malignant, mainly because of their propensity to recur, their crucial location and the fatal clinical course. Although microscopical examination commonly reveals pleomorphism, particularly of cells and nuclei, the histological assessment of malignancy is not always appropriate. The measurement of DNA could provide important information for a classification of their biological behavior (grading). Our examination of a chondroid chordoma revealed a typical diploid DNA curve within a "benign" 4C range concordant to the favorable course of this variant. Our second examination of a "typical" chordoma showed a wide pleomorphism of cell nuclei and moderate proliferation activity within a "low grade" scale. This pointed to a coming (fatal) recurrence 3.5 years after the first surgery. The third chordoma we examined presented an extraordinary 4C aneuploidy with hypertetraploid subpopulations and an increased number of bi- or poly-nucleated tumor cells with prominent nucleoli and some more mitotic figures. In 5 recurrences the DNA pattern remained principally unchanged.