Mammary epithelial hyperplasias: alterations related solely to proliferation?

The cytogenetic analysis of five mammary epithelial hyperplasias is reported. Only two cases had clonal chromosome alterations. Structural alterations involved chromosomes 1 and 5. Numerical alterations involved chromosomes X, 1, 6, 9, and 19. In four cases, the modal number was in the diploid range, and one case was tetraploid. The study of benign proliferations and their comparison with the chomosome alterations of their malignant counterparts could lead to a better understanding of the genes acting solely in cell proliferation and those that cause these cells to undergo malignant transformation and to become invasive.