A 38-year old woman, presents with vaginal bleeding. The patient had amenorrhea for about 12 weeks with uterine enlargment. There was no intrauterine pregnancy. Serum beta hCG is < 1,000 mIU/mL. On H&E sections of the endometrial sample, the tumor consisting of cells haveing a moderate amount of finely granular, eosinophilic to clear cytoplasm with distinct cell membrane and round nuclei.. The proliferation index (Ki67) is < 30%. Which immunostain is most helpful in differentiating this tumor from placental site trophoblastic tumor?

A 42-year female with a history of missed abortion 5 months back presents with lower abdominal pain . Her serum hCG level was slightly elevated. CT showed A solid mass in the lower uterine segment.The patient underwent TAH+BSO. Tumor shows no necrosis, on immunohistochemistry HSD3B and Ki67 positive > 10% cells and negative for p63 and cyclin E. What is the likely diagnosis.