Silver-stained nucleolar organizer regions in the uterine myomatous tumors

The numbers of silver-stained nucleolar organizer regions (AgNORs) were counted in uterine myomatous tumors, and compared with those in corresponding normal myometria. The mean number of AgNORs in myomatous tumors tended to increase according to the neoplastic changes. The mean number of AgNORs in leiomyosarcoma (6.4 ± 0.9) was significantly higher than that in cellular leiomyoma (4.5 ± 0.7, P < 0.01) or leiomyoma (3.0 ± 0.5, P < 0.001). In the normal myometria, the mean number of AgNORs (3.3 ± 0.4) in the premenopausal women showed a higher tendency than that in the post-menopausal women (2.4 ± 0.5). These results therefore suggest that AgNOR counts may be useful for diagnosis of cellular activity in uterine myomatous tumors.