Abstract

A total of 63 uterine leiomyomas were cytogenetically analyzed and, on neighboring tissue pieces, examined histologically. The tumors were dichotomized on the basis of their cellularity (29 normocellular and 34 hypercellular myomas) and on the absence (35 tumors) or presence (28 tumors) of mitoses (1–2 per 10 high-power fields). The cytogenetic analysis revealed normal karyotypes in 39 tumors and clonal chromosome abnormalities in 24. The latter group could be subdivided into cases with a single aberration (9 tumors), cases with more than one aberration but no subclones (8 tumors), and cases with multiple aberrations including subclones (7 tumors). Cytogenetically abnormal leiomyomas were more often hypercellular than cytogenetically normal tumors (17/24 = 71% versus 17/39 = 44%) and also more often had mitoses (16/24 = 67% versus 12/39 = 31%); these differences were statistically significant (p < 0.05). Within the group carrying chromosomal abnormalities, there was a direct linear tendency to the effect that karyotypically complex tumors were more often hypercellular and more often had mitotic figures: 4/9 = 44% of tumors with a single aberration were hypercellular and had mitoses compared with 5/8 = 63% for both parameters in the subgroup with several aberrations but only one clone. The cytogenetic subset characterized by the highest histologic activity were the 7 leiomyomas with clonal evolution giving rise to subclones; all these tumors were hypercellular and had mitoses.