Endometrial adenocarcinoma with choriocarcinomatous differentiation in an elderly virginal woman

A 70-year-old virginal woman underwent hysterectomy and bilateral salpingo-oophorectomy for endometrial carcinoma. Gross examination of the surgical specimen showed normal ovaries and fallopian tubes, an enlarged uterus with several intramural leiomyomata, an endometrium completely carpeted by cancer, and, additionally, a necrotic and hemorrhagic nodular mass that protruded into the endometrial cavity. Histologic examination showed a widespread and superficially invasive, moderately differentiated endometrial adenocarcinoma that merged with a choriocarcinoma. Immunohistochemical studies showed cytoplasmic staining for human chorionic gonadotrophin in syncytiotrophoblast cells, cytotrophoblast-like cells and rare adenocarcinoma cells. A discussion of previously reported similar cases and possible mechanisms of dual differentiation in tumors, as well as comments on histogenesis are included.