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 were used to screen interphase nuclei for numerical chromosome aberrations in histologic thin sections obtained from archival paraffin material of 25 human melanomas of different type, thickness and stage of progression. An alphoid probe for chromosome #3 was applied in four of these tumors. Besides a general large variation of the number of subpopulations of cells characterized by gains and losses of the studied chromosomes, there was a trend to higher variability in metastatic melanomas as compared to small (<1.5 mm thickness) non-metastatic ones and, particularly, to normal skin tissue. Chromosomes #6 and #9 were those often 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 exceeded those with loss of this chromosome in the studied melanomas, but was most pronounced in thicker metastatic tumors.