A case of endometrial carcinoma progressed during pregnancy resulting in fetal death.

Most endometrial carcinomas (ECs) occurring during pregnancy are diagnosed in the first trimester. During the gestation period, progesterone level, which has a protective effect on the endometrium, is found to increase. In EC cases, administering high-dose progesterone is a therapeutic strategy because this hormone can considerably shrink tumors. Herein, the case of a woman in whom EC progressed during pregnancy is reported. Before pregnancy, she was diagnosed with atypical polypoid adenomyoma based on a blind office biopsy. She spontaneously conceived 2 months later, although she was suggested to undergo dilatation and curettage under general anesthesia to confirm the diagnosis. Subsequently, fetal death occurred at 26 weeks. A vaginal delivery was deemed impossible due to vaginal metastasis of EC; thus, cesarean section was performed. Computed tomography revealed multiple lung, pelvic, and inguinal lymph node metastases. Additional biopsy demonstrated poorly differentiated endometrioid carcinoma. She underwent systemic chemotherapy. However, eventually, the disease progressed, resulting in death 11 months after the cesarean section. In the present case, grade 3 EC may have existed before pregnancy, and this condition could have been diagnosed if hysteroscopic resection or total curettage under general anesthesia was performed. Grade 1 tumor may have been eliminated by the high progesterone level maintained during pregnancy, and thus, only grade 3 tumor progressed. Women who wish to preserve their fertility should undergo precise whole endometrial examination. If not, the fetus and mother may consequently experience an eventful clinical course. © The Japan Society of Clinical Oncology 2020.