A Case of Metastatic Low-Grade Endometrial Stromal Sarcoma Treated with Letrozole after Ovarian Ablation by Radiotherapy

A 50-year-old woman was admitted to our hospital due to multiple lung nodules detected incidentally on a chest X-ray. A video-assisted thoracoscopic lung biopsy revealed low-grade endometrial stromal sarcoma (LG-ESS). She had undergone a simple hysterectomy 1 year earlier owing to a diagnosis of adenomyosis. A review of her previous hysterectomy specimen showed not endometriosis but LG-ESS. According to the patient’s levels of serum follicle stimulating hormone and estradiol, she was in the premenopausal state with retained and normally functioning ovaries. She then underwent ovarian ablation by radiotherapy, after which she was administered 2.5 mg of letrozole once per day. Three months later, the size of the metastatic nodules in both lungs had decreased. The patient was followed up for 24 months while continuing on letrozole, and maintained a partial remission. We report herein on a case of metastatic LG-ESS treated with letrozole after ovarian ablation by radiotherapy.