[Topographical differences in cellular DNA content between the radial growth phase and the vertical growth phase of superficial spreading melanoma].

The nuclear DNA content of tumor cells was measured during the radial growth (RGP) and vertical growth (VGP) phases of three cases of superficial spreading melanoma. To compare these two phases, the DNA distribution histogram was analyzed and the DNA index was calculated. A aneuploid population appeared histographically in all specimens of VGP; however, no such abnormal population could be detected in RGP. VGP cells contained greater numbers of polyploid cells and had a higher DNA index value than RGP cells in all cases. These findings support Clark's postulation that the appearance of a new clonal cell population contributes to the development of VGP from RGP in malignant melanoma.