A Case of Early-Stage Lower Uterine Segment Carcinoma With Hysteroscopic Observation of Visual Changes Induced by a Gonadotropin-Releasing Hormone (GnRH) Antagonist.

Endometrial carcinomas in the isthmus are called lower uterine segment (LUS) cancers. It is a rare location among uterine cancers and is known to be associated with Lynch syndrome, which tends to occur at a young age. Preoperative diagnosis may be difficult due to its anatomical location, and the prognosis is poorer than that of uterine cancer in general. Gonadotropin-releasing hormone (GnRH) antagonists, through their strong suppression of sex hormone release, prove advantageous as preoperative medication, ensuring optimal visualization in hysteroscopic surgery. We have encountered a case of early-stage LUS cancer diagnosed postoperatively after hysteroscopic surgery modified by GnRH antagonist treatment. In this report, we describe the characteristics of the visual findings of hysteroscopy, along with a literature review. The patient, a 32-year-old nulliparous woman, was referred to our facility after multiple endometrial polyps with atypical blood vessels were detected during a hysteroscopy performed during infertility treatment at her primary clinic. As endometrial cytology was negative, hysteroscopic tumor resection was performed after a short course of GnRH antagonist therapy. Lesions observed during hysteroscopy were broad-based with a scar-like white appearance and no abnormal blood vessels. Malignancy was not suspected until postoperative pathology confirmed grade 2 endometrioid cancer. For early detection of LUS cancer, it is worth familiarizing with its findings under hysteroscopy and the changes in appearance related to hormonal changes.