Detection of numerical chromosomal aberrations in malignant melanomas using fluorescence in situ hybridization.

To evaluate the numerical chromosomal aberration in malignant melanoma, we have applied fluorescence in situ hybridization (FISH) with repetitive DNA probes specific for chromosomes 1, 6, 7, 9, 10, and 17 on 24 fresh malignant melanomas (primary: 14, metastatic: 8). We defined a tumor that had copies with more than 3 spots as chromosomal gain. Chromosomal copy number gain was found in 40.9% of the cases for chromosome 7, 27.2% for chromosome 6, 27.2% for chromosome 17, 22.7% for chromosome 9 and 10, and 4.5% for chromosome 1. Monosomy was found in 54.5% of the cases for chromosome 10, 36.5% for chromosome 9, 27.2% for chromosome 6, 22.7% for chromosome 17, and 18.1% for chromosome 1 and 7. The most frequent numerical alterations were seen in chromosomes 6, 7, 9 and 10. Gain of chromosome 6 and 7 and/or losses of chromosome 9 and 10 may play an important role in the tumorigenesis and development of malignant melanomas.