A Large High-Grade Endometrial Serous Carcinoma with Yolk Sac Tumor Differentiation in a Post- Menopausal Woman: Case Report

Abstract Introduction/Objective Yolk sac tumors are germ cell tumors mostly arising in the ovary or vagina, with cases reported throughout the gynecological tract. Only few cases were reported to arise in the endometrium and even fewer admixed with a conventional carcinoma especially in postmenopausal women. Yolk sac tumor-like areas are considered a form of retro-differentiation. Here we report a case of high-grade serous carcinoma of the endometrium with yolk sac differentiation in a postmenopausal woman. Methods/Case Report An 82-year-old Caucasian female presented with postmenopausal bleeding and a 17.6 cm endometrial mass. Total abdominal hysterectomy and bilateral salpingo-oophorectomy was performed. A large markedly necrotic friable mass occupied the entire endometrial cavity. Microscopic examination revealed a noninvasive carcinoma arising within a polyp. Tumor cells showed two different distinct morphologic patterns, including a predominantly high-grade serous carcinoma with scant foci of clear cell component, admixed with areas of squamous/eosinophilic-like morphological pattern. The latter was diffusely positive for p53, p16, AE1/AE3 and CK7, focally positive for CK5/6, GATA3, HepPar1 , AFP , PLAP , PAX8, CD30 and SALL4 , while negative for desmin, ER, PR, Napsin A, HCG, p40, p63, C-Kit, HMB45, S100, and Melan A. Mismatch repair proteins expression was intact throughout the entire tumor. Serum AFP level measured three weeks after surgery was within normal range. Results (if a Case Study enter NA) NA Conclusion Highlighting the yolk sac tumor differentiation in endometrial carcinoma is very challenging and requires a thorough immunohistochemical evaluation combined with morphologic assessment.