DNA histogram typing in retinoblastomas and neuroblastomas.

The nuclear DNA content characterization was carried out by means of both DNA index and DNA histogram type assessments in a series of 21 retinoblastomas, 11 neuroblastomas, 1 ganglioneuroblastoma, and 4 medulloblastomas. These measurements were performed by means of the cytophotometric digital cell image analyses of Feulgen-stained nuclei. The results indicate that as far as nuclear DNA content is concerned, retinoblastomas seem to be very different from neuroblastomas. In fact, in terms of DNA index, retinoblastomas are significantly more aneuploid than neuroblastomas. The DNA histogram type shows that the high level of aneuploidy found in retinoblastomas corresponds to genotypically polymorphic tumors, and this could reflect a serious degeneration of the genomic material in retinoblastomas. This type of degeneration seems to be much less frequent in neuroblastomas, which basically seem to be either diploid or hypertriploid.