EPITHELIOID CELL MELANOMAS HAVE GREATER DNA-PLOIDY ABNORMALITIES THANSPINDLE-CELL MELANOMAS - CYTOLOGICAL EVIDENCE FOR A HIGHER MALIGNANT POTENTIAL OF THE FORMER

The cellular DNA ploidy of 30 cases of malignant, melanoma was measure d by 4',6-diamidino-2-phenylindole-DNA (DAPI-DNA) microfluorimetry. DN A histograms and DNA index values were compared among melanomas of dif ferent cell morphology. Epithelioid cell melanomas often showed greate r DNA aneuploidy, than spindle cell melanomas in terms of histographic pattern. DNA index values of the former (mean +/- standard error, 1.8 4 +/- 0.31) were significantly higher than those of the latter (1.55 /- 0.24; P < 0.05). The DNA index values of mixed-type melanomas were intermediate. These results indicate that the epithelioid cell melanom as have greater DNA ploidy abnormalities which are usually correlated with a grater malignant potential in pigmentary neoplasms. Thus our re sults confirm clinical evidence that melanoma patients with the epithe lioid type of cells have a poorer prognosis than those with the spindl e type of cells.