CHROMOSOME GAIN AND LOSS IN PARAFFIN SECTIONS FROM MALIGNANT MELANOMAS OF THE SKIN

Alphoid DNA probes specific for the chromosomes #6, #7, #9, and #17 we re used to screen interphase nuclei for numerical chromosome aberratio ns in histologic thin sections obtained from archival paraffin materia l of 25 human melanomas of different type, thickness and stage of prog ression. An alphoid probe for chromosome #3 was applied in four of the se tumors. Besides a general large variation of the number of subpopul ations of cells characterized by gains and losses of the studied chrom osomes, there was a trend to higher variability in metastatic melanoma s as compared to small (<1.5 mm thickness) non-metastatic ones and, pa rticularly, to normal skin tissue. Chromosomes #6 and #9 were those of ten affected by loss in thick melanomas (>2 mm), while subpopulations showing a gain of these chromosomes, and, in addition, of chromosome # 7 seemed more frequently to be associated with thin and non-metastatic ones. The frequency of cases showing gain of chromosome #17 clearly e xceeded those with loss of this chromosome in the studied melanomas, b ut was most pronounced in thicker metastatic tumors.