Primitive neuroectodermal tumors of the uterus: a report of four cases.

Four cases of primitive neuroectodermal tumor (PNET) of the uterine corpus are reported, bringing the total number of reported PNETs in this site to seven. The four women were in their seventh decade of life and presented with abnormal vaginal bleeding and, in two cases, an enlarged uterus. The patients underwent total or subtotal abdominal hysterectomy and bilateral salpingo-oophorectomy and, in one patient, pelvic lymphadenectomy. Three patients received postoperative radiation therapy, chemotherapy, or both. Gross examination revealed fleshy polypoid masses filling the endometrial cavity and, in two cases, deeply invading the myometrium. Histologic, immunohistochemical, and, in two cases, ultrastructural examination revealed typical PNETs that exhibited variable degrees of neural, glial, ependymal, and medulloepithelial differentiation. Two PNETs were admixed with other neoplasms: in one case a grade I endometrial adenocarcinoma and in the other a low-grade endometrial stromal sarcoma. The prognosis of the tumors was related to their stage: two patients with stage I tumor were alive with no evidence of disease at 5 and 6 years, whereas two patients with stage III or IV tumor died of tumor at 6 and 12 months. Although it has been suggested that uterine PNETs may be derived from displaced germ cells or implanted fetal tissues, evidence provided by this study, including the advanced ages of the patients and an admixture with neoplasms of unquestioned müllerian origin, suggests a müllerian origin for these tumors in at least some cases.