Abstract

Estrogen receptor(ER) and progesterone receptor(PR) were studied immunohistochemically using specific antireceptor monoclonal antibodies in leiomyomas and myometrium from same patients from 38 women in various stages of the menstrual cycle, menopause and pregnancy. Two postpartum uteri are also included. Immunohistochemical localization was quantified as to intensity of staining and tissue distribution, and the results were compared with those of PCNA index. In all samples, ER and PR localized within the nuclei of target cells. The histochemical score of ER in leiomyoma was significantly greater than that found in myometrium. But ER in leiomyoma was expressed in cyclic fashion(r=0.45, P=0.006), like as in myometrium, throughout the menstrual cycle, paralleled by a concomitant, though delayed. In contrast, PR content constantly maintained in myometrium and leiomyoma throughout menstrual cycle, and there was no significant difference between them. However, leiomyoma and myometrium of pregnancy showed a significant reduction in the amount of ER and PR localized. PCNA index in leiomyoma(14.9+/-24.4) was also significantly higher than that found in myometrium(2.1+/-3.3). The index declined throughout the secretory phase. The leiomyoma had increased PCNA index during pregnancy, while the increasing rate in leiomyoma was lower than that of myometrium. The growth potential of leiomyomas is appearently higher than that of myometrium under the high progesterone level. The most of neoplasm with high PCNA index(10 above) contained absolute or relative abundant PR or ER content. Alteration of receptor content may be an important mechanism in steroid dependent growth of leiomyoma and may provide information useful in the clinical management of this neoplastic disorder.

• Keywords: Estrogen receptor;Progesterone receptor;PCNA;Leiomyoma;Myometrium