Examination of clonal variants from human malignant melanoma studied by chromosome banding analysis

Multiple metastatic melanoma lesions from three patients were cytogenetically characterized in order to assess the degree of intra-patient karyotypic heterogeneity. A total of 20 specimens were analysed: 12 samples from patient No. 1, five samples from patient No. 2, and three samples from patient No. 3. Sufficient mitoses were obtained to perform detailed analysis in 19/20 specimens following short-term culture. The modal chromosome number of all three cases was near-diploid, with all samples demonstrating multiple structural abnormalities. Abnormalities shared by all three patients were alterations of chromosomes 1 and 8. Other structural abnormalities common to two of the three patients involved chromosomes 6, 7, 9 and 10. Minor intra-tumour karyotypic variation was detected in all three cases. However, the majority of clonal alterations were retained in all metastatic lesions, clearly indicating the karyotypically stable and clonal nature of this neoplasm.