Ultrastructure of papillary serous carcinoma of the endometrium

Three cases of papillary serous carcinoma of the endometrium ( PSCE ) have been studied by transmission electron microscopy, and the ultrastructural findings compared with those in classical "endometrioid" carcinoma of the endometrium ( CECE ) and papillary serous carcinoma of the ovary ( PSCO ). PSCE possesses many ultrastructural features in common with both CECE and PSCO , as well as with clear cell carcinoma of the endometrium, emphasizing the close relationship existing among these different tumors of Müllerian origin. The only useful ultrastructural distinguishing features between serous and endometrioid carcinomas of similar histologic grade are more numerous secretory granules in the former and prominent paranuclear microfilaments and tonofilaments in the latter. Despite its lack of ultrastructural distinctiveness, the clinical behavior of PSCE justifies its consideration as a unique clinicopathologic entity.