Significance of papillary (villoglandular) differentiation in endometrioid carcinoma of the uterus.

The frequency, topography, and significance of papillary (villoglandular) differentiation were examined in 142 cases of endometrioid (typical) carcinoma of the endometrium. Forty-four (31%) of the 142 cases showed papillary differentiation, including eight carcinomas limited to the endometrium and 36 cases with myometrial invasion. In 24 (67%) of the 36 cases with myometrial invasion, papillary differentiation was found in both the endometrial component of the carcinoma and in tumor invading the myometrium. In the remaining 12 cases, papillary differentiation was found in the endometrial component but not in tumor invading the myometrium, which showed either glandular or solid growth patterns. When patients were divided into two groups based on the presence or absence of papillary differentiation, regardless of its location, the two groups did not differ in prognosis or frequency of pathologic changes associated with outcome. In the subgroup of patients with tumors showing myometrial invasion, however, endometrioid carcinomas displaying papillary differentiation in the myometrium were associated with a higher frequency of vascular invasion (p = 0.007), a higher rate of lymph node metastasis (p = 0.001), and worse outcome (p = 0.05) compared with carcinomas showing myometrial invasion in the form of glandular or solid patterns regardless of the presence or absence of papillary differentiation in the endometrium. The results of the present study suggest that papillary differentiation is of significance in endometrioid carcinoma. If these findings can be confirmed, a separate designation for these tumors as "papillary endometrioid carcinomas" or "villoglandular endometrial carcinomas" would be helpful if use of these terms was limited to endometrioid carcinomas manifesting papillary differentiation in the myometrium.