Nuclear deoxyribonucleic acid content (ploidy) of endodermal sinus (yolk sac) tumor.

Paraffin sections from 30 endodermal sinus (yolk sac) tumors were Feulgen-stained, and nuclear DNA content (ploidy) was assessed through DNA cytophotometry using the microTICAS image analysis system. The series consisted of 20 ovarian, 8 testicular, 1 sacrococcygeal, and 1 mediastinal tumors. Of the 30 endodermal sinus (yolk sac) tumors 29 were shown to be aneuploid, whereas the remaining tumor which exhibited the recently described primitive intestinal or enteric pattern was diploid and may thus be considered a neoplasm showing a somewhat higher degree of differentiation as compared to tumors showing the other histologic patterns of endodermal sinus (yolk sac) tumors.