BCL-2 and PAX2 Expressions in EIN which Had Been Previously Diagnosed as Non-Atypical Hyperplasia

The relationship between PAX2 and another anti-apoptotic gene, BCL-2, has been shown in a limited number of studies. The aims of this study are to investigate the value of PAX2 and BCL-2 expressions in lesions which have been defined as nonatypical hyperplasia in terms of detecting EIN and to evaluate the relations of these proteins in EIN. For this purpose, 108 cases of non-atypical endometrial hyperplasia diagnosed from 2006 to 2011 were re-evaluated. Immunohistochemical studies with PAX2 and BCL-2 were performed in 20 cases with EIN and 34 cases with benign hyperplasia. The mean BCL-2 immunohistochemistry scores of benign hyperplasia and EIN cases were 4.06 ± 1.04 and 4.63 ± 2.03, respectively. The mean BCL-2 score of EIN cases was significantly higher than benign hyperplasia (p = 0.021). The mean PAX2 scores of benign hyperplasia and EIN cases were 4.32 ± 1.07 and 2.19 ± 2.34, respectively. The mean PAX2 scores of EIN cases were significantly lower than benign hyperplasia (p = 0.001). BCL-2 expression was increased compared to normal endometrium in 66.7% of EIN cases, and PAX2 expression was decreased in 73.3%. Consistent with this, in 60% of cases, BCL-2 expression was increased compared to normal endometrium, while PAX2 expression was decreased. BCL-2 and PAX2 protein expression changes occur in early phases of endometrial tumorigenesis. These changes are often seen as a simultaneous increase in BCL-2 expression and decrease in PAX2 expression.