Large cervical endometrioid adenocarcinoma mimicking endometrial endometrioid adenocarcinoma: A case report.

Endometrioid adenocarcinoma of the uterine cervix is rare and difficult to distinguish from endometrial adenocarcinoma, particularly in large bulky cases. Herein, we report a rare case of a large endometrioid adenocarcinoma in a 58-year-old Japanese woman in which the tumor origin was difficult to identify. The patient presented with abdominal pain and vaginal bleeding and was referred to a gynecologist for suspected uterine cancer based on an evaluation performed at another institution. Imaging studies revealed an 11-cm cervical tumor without parametrial invasion, lymph node, distant metastases, or hydronephrosis, whereas cervical biopsy revealed an endometrioid adenocarcinoma. The patient was subsequently referred to our department for the determination of the tissue origin. The results of immunohistochemical staining were equivocal for cervical and endometrial origin. However, rectal examination confirmed a barrel-shaped cervix extending from the lower uterine segment to the hymenal ring. Human papillomavirus and microsatellite instability tests were negative. Finally, the patient was diagnosed with stage III endometrioid adenocarcinoma of the uterine cervix and achieved complete remission after concurrent chemoradiotherapy, followed by platinum-based systemic chemotherapy.