Immunohistochemical detection of estrogen and progesterone receptors in endometriotic tissue. A comparative study of paraffin embedded and fresh frozen tissues.

30 formalin-fixed and paraffin embedded and 20 fresh frozen samples of endometriotic tissue were analysed immunohistochemically for the concentration of estrogen and progesterone receptors. In the formalin-fixed and paraffin embedded group only 37% of the samples were estrogen receptor positive whereas 63% were receptor negative. In contrast, we found that 67% of the samples had a positive progesterone receptor status. In the fresh frozen group 60% of endometriotic tissues were estrogen receptor positive and 75% of the tissues had a positive progesterone receptor status. We could not find any correlation between the site or severity of the endometriosis or the hormonal receptor status. We were able to demonstrate that the immunohistochemical detection of hormonal receptors in endometriotic tissues is possible and that better results were obtained if fresh frozen rather than formalin-fixed and paraffin embedded tissues were analyzed.