Endometrial foam cells. Non-estrogenic and estrogenic

Four patients with endometrial foam cells are described. In one the endometrium was obtained after parturition. It showed decidua and endometritis, whereas in the second patient, who had received birth control medication in the past, the endometrium was proliferative. In both cases there was a considerable amount of endometrial hemorrhage. The foam cells in these two patients had little granularity, and their cytoplasm contained hemosiderin. The other two patients received exogenous estrogen and presented with endometrial hyperplasia and adenocarcinoma. In these latter cases the foam cells were more granular, and contained no hemosiderin. Our findings confirm the presence of two types of histologically similar endometrial foam cell: a histiocytic, "non-estrogenic" reactive type capable of phagocytosis, and a stromal, "estrogenic" non-phagocytic type which is associated with hyperplasia or carcinoma and which may also be related to estrogen administration. Staining for hemosiderin may be particularly helpful in differentiating between the two types of foam cell. Such a differentiation is of practical importance because of the biologic significance attached to the "estrogenic" foam-cells which are usually indicative of endometrial hyperplasia or carcinoma.