Primary endodermal sinus tumor of the endometrium. A clinicopathologic, immunocytochemical, and ultrastructural study.

We report a case of primary endodermal sinus tumor (EST) of the endometrium in a 42-year-old female. Although numerous extragonadal EST have been reported, primary EST of the endometrium is exceedingly rare. To our knowledge this is the fourth documented case of this nature. The tumor had the typical microscopic features of EST, with papillary, tubular, reticular, and solid growth patterns; occasional Schiller-Duval bodies and many intracellular and extracellular periodic-acid Schiff positive hyaline globules were seen. The neoplastic cells stained positively for alpha-fetoprotein (AFP), alpha-1-antitrypsin (A1AT), cytokeratin, and placental alkaline phosphatase. The globules were positive for AFP, A1AT, albumin, transferrin, and fibronectin. The tumor cells were negative for type IV collagen and the beta subunit of human chorionic gonadotropin (B hcG). Electron microscopic examination showed intracellular and extracellular basement membrane-like material, intracytoplasmic lumina with microvilli, and glycogen. The patient was treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy, followed by four cycles of adjunct chemotherapy (vinblastine, bleomycin, and cisplatinum) repeated every 3 weeks. The serum AFP level was elevated significantly before the surgery and the tumor response was monitored by serial determination of serum AFP level. There was no evidence of recurrence 24 months after surgery.