FDG PET/CT in a Case of Primary Ewing Sarcoma of the Uterus

A 23-year-old woman presented with prolonged menstruation for 10 days. Pelvic ultrasound showed multiple masses in the uterus, suspicious for leiomyomas. Pelvic MRI showed an irregular multinodular uterine mass involving the cervix, and bilateral enlarged extrailiac lymph nodes, suggesting uterine malignancy with lymph node metastases. FDG PET/CT showed heterogeneous activity of the uterine mass and multiple FDG-avid lymph nodes in the bilateral pelvic and retroperitoneal regions, suggesting uterine malignancy with multiple lymph node metastases. Hysterectomy, bilateral salpingo-oophorectomy, and pelvic and retroperitoneal lymph node dissection revealed EWSR1-rearranged Ewing sarcoma of the uterus and no malignancy in the resected lymph nodes.