Cytogenetic description of breast fibroadenomas: alterations related solely to proliferation?

Twelve breast fibroadenomas were analyzed cytogenetically and only four wer e found to have clonal alterations. The presence of chromosomal alterations in fibroadenomas must be the consequence of the proliferating process and must not be related to the etiology of this type of lesion. In contrast, th e few fibroadenomas that exhibit chromosomal alterations are likely to be t hose presenting a risk of neoplastic transformation. Clonal numerical alter ations involved chromosomes 8, 18, 19, and 21. Of the chromosomal alteratio ns found in the present study, only monosomy of chromosomes 19 and 21 has b een reported in breast fibroadenomas. The loss of chromosome 21 was the mos t frequent alteration found in our sample. The study of benign proliferatio ns and their comparison with chromosome alterations in their malignant coun terparts ought to result in a better understanding of the genes acting on c ell proliferation alone. and of the genes that cause these cells to exhibit varied behaviors such as recurrences, spontaneous regression and fast grow th.