Morphologic Correlates of Host Response in Endometrial Carcinoma *

Cases of endometrial carcinoma reviewed for this study were divided into two groups: 1) Premenopausal, perimenopausal and postmenopausal patients in whom a history of anovulation, obesity, ovarian hyperthecosis (including Stein‐Leventhal syndrome) or feminizing tumors, and/or exogenous estrogen intake were found; and 2) postmenopausal, elderly patients, without known hormonal or metabolic disturbances and without any history of estrogen therapy. In the first group, frequent associated findings were precursor stages of endometrial carcinoma, such as adenomatous and atypical hyperplasia. In the majority of cases, the cancer was confined to the endometrium, rarely infiltrating the myometrium. In the second group, the cancer was associated most often with an inactive, atrophic endometrium and frequently diffusely infiltrated through the myometrium, with lymphatic and vascular involvement. The lymphatic and plasma‐cell infiltrate was evaluated in both groups. It was found to be more abundant in the first group, both at the tumor‐host interface and perivascularly, than in the second. As reported in other malignancies of the female reproductive system, the presence or absence of a lymphocytic infiltrate as a morphological expression of local cellular immune response of the host correlates well with the biological behavior of the tumor. A challenging question is the relationship, if any, between hormonal factors and immune mechanisms in tumors arising in tissues such as the endometrium that, even normally, are targets of hormonal stimulation.