Are there any differences in the expression of hormonal receptors and proliferation markers between uterine and extrauterine leiomyomas?

The aim of this study is to determine the immunohistochemical expressions of estrogen receptor, progesterone receptor, and Ki-67 proliferation marker in 8 extrauterine leiomyomas and to compare these values with their uterine counterparts. In all, 8 patients with extrauterine leiomyomas and 20 patients with uterine leiomyomas as a control group were studied. Sections were immunohistochemically stained with estrogen receptor, progesterone receptor, and Ki-67 antibodies. Labeling indices for estrogen receptor, progesterone receptor, and Ki-67 were found to be 33.05 % ± 31.70%, 14.18 % ± 18.80%, and 0.52 % ± 1.32% for extrauterine leiomyomas and 65.09% ± 26.65%, 32.53% ± 32.80%, and 0.37% ± 0.71% for uterine leiomyomas, respectively. The difference of labeling indices for progesterone receptor between uterine leiomyomas and extrauterine leiomyomas was statistically significant (P =.002). This study shows that increased expression of progesterone receptor is observed only in uterine leiomyomas during the reproductive period. However, it seems that additional factors to hormone receptors contribute to the development of extrauterine leiomyomas. © 2008 Sage Publications