Polyploidy in malignant melanoma

Chromosome studies were performed on primary or metastatic malignant melanoma from 6 patients. All of them were aneuploid and had either hyperdiploid, near triploid, tetraploid, or hypertetraploid cell lines. Two of them had definite stem‐cell lines, but the other 4 cases had a wide distribution of chromosome numbers with no apparent cell lines. Three of the 6 patients had one or more marker chromosomes, i.e., large submetacentrics or long acrocentrics. These results lead us to speculate that the rapid cell growth is due not only to selection but also to continuous replication defects and mitotic abnormalities.