Immunohistochemical Estrogen Receptor Assessment in Hyperplastic, Neoplastic, and Physiologic Endometria

Summary Endometrial hyperplasias and some endometrial carcinomas arise in a setting of estrogen excess. Steroid hormones interact with cells via specific receptors; assessing receptor levels may indicate a tissue's potential for interaction with that hormone. To examine estrogen receptor (ER) levels in endometrial hyperplasia, endometrial carcinoma, and physiologically cycling endometrium, an immunohistochemical technique utilizing a monoclonal anti-estro philin (estrogen receptor) antibody was applied to formalin-fixed, paraffinembedded tissue. In complex hyperplasia and grade I adenocarcinoma, the mean percentages of epithelial cells demonstrating nuclear staining for ER was mildly decreased compared to proli f erative endometrium. A trend was noted toward less ER staining in atypical hyperplasia compared to non-atypical complex hyperplasia. ER varied with physiologic cycling of the endometrium. ER was also present in atrophic endometrium, myometrium, adenomyosis, and leiomyomata. Immunohistochemistry permits localization of ER and is a useful technique in ER assessment of endometrial hyperplasias and carcinomas.