IntroductionEndometrial stromal sarcoma (ESS) is a rare malignancy of uterine in middle aged women. There are numerous subtypes for ESS which share the same clinical picture of uterine bleeding and pelvic pain. Consequently, diagnosis and treatment modalities of LG-ESS with metastasis are challenging. However, both molecular and immunological study of samples can be useful.Case presentationIn this case study, we report a 52-year-old woman presenting with the chief complaint of unusual uterine bleeding. There was no specific finding in her past medical history. The CT study revealed enlarged bilateral ovary with a significantly large left ovarian mass and suspicious mass in uterus. By the diagnosis of ovarian mass, patient went under total abdominal hysterectomy with bilateral salpingo-oophorectomy (BSO), greater omentectomy, and appendectomy followed by post-op hormone therapy. Her follow-up was uneventful. The IHC and pathological study of samples revealed incidental LG-ESS uterus mass with metastasis to ovaries despite her primary diagnosis.DiscussionLG-ESS has low metastasis rate. Surgical modalities and neoadjuvant therapies are recommended base on the stage of ESS. In the following study, we represent a case of incidental LG-ESS with bilateral ovarian invasion who was initially diagnosed as an ovarian mass.ConclusionOur patient was successfully managed by surgical intervention. Despite scarcity of LG-ESS, it is advised to consider LG-ESS as a differential diagnosis in management of patients with a uterus mass with bilateral ovarian involvement.