KARYOTYPIC ABNORMALITIES IN FIBROADENOMAS OF THE BREAST

Short-term cultures of 50 fibroadenomas of the breast were cytogenetic ally analyzed. Nine tumors were found to display clonal chromosome abe rrations. One had multiple, cytogenetically unrelated clones, whereas the others had a single abnormal clone each. Four cases had one balanc ed translocation as the sole anomaly, and one had a complex intrachrom osomal rearrangement of chromosome 3, leading to loss of 3p material. One fibroadenoma had a single numerical aberration, and one had supern umerary ring chromosomes. The remaining 2 cases had both numerical and structural aberrations. The only recurrent alterations were trisomy 2 0 and rearrangement of chromosome arm 1 p. The finding of similar chro mosomal aberrations in fibroadenomas and carcinomas suggests that wome n with karyotypically abnormal fibroadenomas may have an increased ris k of developing subsequent breast cancer. If so, different chromosome anomalies might have different pathogenetic and/or prognostic signific ance. (C) 1997 Wiley-Liss, Inc.