Comparison of estrogen and progesterone receptor, Ki-67, and p53 immunoreactivity in uterine endometrioid carcinoma and endometrioid carcinoma with squamous, mucinous, secretory, and ciliated cell differentiation.

An analysis of 77 uterine endometrioid carcinomas was performed to compare pure endometrioid carcinomas and endometrioid carcinomas with various types of cellular differentiation for the expression of estrogen (ER) and progesterone (PR) receptors, p53, and Ki-67 and to correlate these findings with clinicopathologic features. Forty-three pure endometrioid carcinomas and 34 endometrioid carcinomas displaying additional types of cellular differentiation in at least 10% of the tumor (16 squamous, 11 mucinous, four ciliated cell, and three secretory) were analyzed. In 8 of the 16 tumors with squamous differentiation, the squamous component was histologically benign (low grade), and in eight tumors it was histologically malignant (high grade). In tumors showing various types of cellular differentiation except those with a high-grade squamous component, comparison of the endometrioid glandular component with the squamous, mucinous, secretory, and ciliated cell components showed that ER/PR, Ki-67, and p53 expression were generally higher in the glandular component compared with the various differentiated components. These findings parallel the changes that occur in the endometrium in the secretory phase of the menstrual cycle and, therefore, suggest that the differentiated components have undergone terminal differentiation. In contrast, in endometrioid carcinomas with a high-grade squamous component, Ki-67 and p53 expression were the same in the glandular and squamous components suggesting that squamous epithelium in these tumors represented another pathway of cellular differentiation but not one that was terminally differentiated. Endometrioid carcinomas with a high-grade squamous component had significantly higher grade (P = .002), stage (P < .001), cellular proliferation index (P = .0005), and worse outcome (P = .0009) compared with tumors with the other types of cellular differentiation, including those with a low-grade squamous component and pure low-grade endometrioid carcinomas. In addition, carcinomas with a high-grade squamous component occurred in older women and were more frequently associated with atrophic endometrium and less replacement hormone therapy, but the differences were not statistically significant. In conclusion, endometrioid carcinomas with various types of cellular differentiation can be broadly divided into two groups. Tumors with mucinous, secretory, and ciliated cell differentiation and those with a low-grade squamous component are similar to pure low-grade endometrioid carcinomas in that most have high ER and PR expression, low cellular proliferation indices, low p53 immunoreactivity, and good prognosis. In contrast, endometrioid carcinomas with a high-grade squamous component lack expression of ER and PR, have high cellular proliferation indices, often express p53, and have a prognosis similar to poorly differentiated endometrioid carcinomas.