Immunohistochemical expression of estrogen and progesterone receptors in endometrial hyperplasia and endometrioid carcinoma

Endometrial carcinoma (EC) is the most common gynecologic malignancy; however, mechanisms underlying its pathogenesis remain obscure. Endometrial carcinoma has been classified into two major categories: type I (related to estrogen or endometrioid adenocarcinoma) and type II (unrelated to estrogen). Estrogen is the main trigger for the abnormal proliferation in the endometrial epithelium but progesterone can inhibit this process. The aim of this study was to analyze the expression of estrogen and progesterone receptors in all types of endometrial hyperplasia in comparison to endometrioid adenocarcinoma of endometrium.

Forty-seven specimens including 23 cases of histopathologically confirmed hyperplastic endometrium (12 simple hyperplasia, 5 complex hyperplasia without atypia, and 6 complex hyperplasia with atypia) and 24 cases of endometrial carcinoma were studied. Immunohistochemical staining of estrogen and progesterone receptors was performed in paraffin-embedded blocks and expression of estrogen and progesterone receptors were scored according to the proportion of positive staining cells.

Overexpression of progesterone receptors was seen in 18 (75%) out of 24 cases of endometrial carcinoma and 23 (100%) of all types of endometrial hyperplasia. The aforesaid differences were statistically significant (P=0.023). 70.8% of cases with endometrial carcinoma were 3+ for immunohistochemical staining of progesterone receptors as were 85.7% of the cases with endometrial hyperplasia; the difference being also statistically significant (P=0.02).

Considering the increased proportion of progesterone receptor expression in all types of hyperplastic endometrium in comparison to endometrial carcinoma, hormonal therapy by progestinal agents is recommended as a treatment of choice.