Immunohistochemical characterization of proliferation, oestrogen receptor and progesterone receptor expression in endometriosis: comparison of eutopic and ectopic endometrium with normal cycling endometrium

Recent studies examining oestrogen and progesterone receptorstatus and the proliferative activity of endo-metriotic lesionshave produced conflicting reports. This study aimed to clarifythe receptor status and proliferative activity of eutopic andectopic endometrium from women with endometriosis and endometriumfrom normal women. Progesterone and oestrogen receptor expressionand proliferative activity were studied in eutopic and ectopicendometrium from 30 women with endometriosis and in endometriumfrom 30 normal cycling women using microwave-pretreated paraffin-embeddedsections stained with an avidin-biotin peroxidase technique.Progesterone and oestrogen receptor expression in the controlendo-metrium did not differ from that of eutopic endometriumfrom women with endometriosis. Oestrogen receptor expressionin ectopic endometrium increased from the proliferative to thelate secretory phase. Epithelial progesterone receptor expressiondecreased during the cycle. Oestrogen receptor expression inboth epithelium and stroma of ectopic endometrium was significantlyhigher than in eutopic endometrium throughout the cycle. Incontrast, stromal progesterone receptor expression tended tobe reduced in ectopic endometrium compared with eutopic tissue.Epithelial progesterone receptor expression was increased inectopic endometrium but only in the late secretory phase. Althoughproliferative activity in the epithelium of control and eutopicendometrium was reduced from the proliferative to the late secretoryphase, stromal activity did not vary. The proliferative activityin ectopic endometrium remained low and constant throughoutthe cycle. In the proliferative and early secretory phases,the proliferative activity of eutopic endometrium was increasedcompared with ectopic endometrium, but in the late secretoryphase, levels were comparable. These findings challenge previousreports which have suggested that oestrogen receptors are reducedin ectopic tissue. This may have clinical implications for thedevelopment of novel treatments for endometriosis.