A rare case of high-grade endometrial stromal sarcoma initially misdiagnosed as a uterine fibroid in a postmenopausal woman

Abstract

Introduction: High-grade endometrial stromal sarcoma (HG-ESS) is a rare and aggressive malignant neoplasm that has a poor prognosis and accounts for 0.2% of uterine malignancies. There is a lack of available information on HG-ESS due to its high case fatality rate. Due to the poor prognosis associated with HG-ESS, it is important to diagnose HG-ESS in its early stages. Case Report: In this case report, we describe the case of a 63-year-old postmenopausal woman who presented with a pelvic mass and postmenopausal bleeding. The patient’s past history included a fibroid for which the patient underwent a successful uterine fibroid embolization. The patient underwent a pelvic ultrasound and an endometrial biopsy prior to gynecological consult. Both were inconclusive and led to an initial diagnosis of a uterine fibroid. After a gynecological consult and an additional biopsy, pathological examination revealed high-grade neoplastic cells that expressed strong and diffuse nuclear BCL1/Cyclin D1. The pattern of diffuse cyclin D1 expression and negative CD10 was suggestive of the YWHAE-rearranged subtype of HG-ESS. The combined morphologic and immunophenotypic features were consistent with a high-grade endometrial stromal sarcoma with fluorescence in situ hybridization (FISH) positivity for YWHAE gene rearrangement and FISH negativity for BCOR gene rearrangement. The patient underwent a robotic-assisted modified radical hysterectomy, radical pelvic tumor resection, bilateral salpingo-oophorectomy, sentinel pelvic lymph node dissections, and an appendectomy. The resulting surgical pathologic diagnosis was HG-ESS stage 1. Currently, no adjuvant therapy is recommended given negative margins with stage 1 status. Conclusion: High-grade endometrial stromal sarcoma is a rare clinical entity in postmenopausal women which is initially misdiagnosed but should be included in the differential diagnosis of necrotic masses.