Cytogenetic abnormalities in uterine myomas are associated with myoma size.

Uterine leiomyomata (myomas) are associated with a variety of characteristic cytogenetic abnormalities. The significance of these chromosomal aberrations in the pathobiology of myomas remains to be determined. The present study investigated the relationship between myoma cytogenetic abnormalities and size. A total of 114 myoma specimens were obtained from 92 patients undergoing myomectomy or hysterectomy. The maximum diameter of each myoma was measured and a portion of each myoma obtained for cytogenetic analysis. Karyotypes were analysed and categorized as normal, abnormal (non-mosaic) or mosaic. Cytogenetic analyses revealed 73 (64%) normal, 20 (18%) abnormal (non-mosaic), and 21 (18%) mosaic karyotypes. Mean myoma diameter was 6.5+/-0.44 cm with a range of 0.4-27 cm. Differences between the mean myoma diameter of specimens with normal versus abnormal karyotypes was determined by the Kruskal-Wallis test. The mean myoma diameter among specimens with abnormal (non-mosaic) karyotypes was significantly greater than myomas with normal karyotypes (10.2+/-5.9 versus 5.9+/-4.2 cm; P < 0.001). The proportion of abnormal (non-mosaic) karyotypes in myomas >6.5 cm was compared to myomas <6.5 cm by chi2-analysis; myomas >6.5 cm demonstrated a significantly higher proportion of abnormal (non-mosaic) karyotypes when compared to myomas <6.5 cm (75 versus 34%; P < 0.02). In summary, a significant relationship exists between clonal cytogenetic abnormalities and myoma size, suggesting that chromosomal abnormalities associated with individual myomas enhance myoma growth.