Case Report: Metastasis of low-grade endometrial stromal sarcoma to the inferior vena cava and right atrium: a case of successful one-stage surgical resection with favorable early outcome.

Low-grade endometrial stromal sarcoma (LGESS) is a rare uterine malignancy; metastasis to the inferior vena cava (IVC) and right atrium is exceptionally rare and presents significant diagnostic and therapeutic challenges. We report the case of a 37-year-old woman presenting with progressive abdominal mass enlargement, palpitations, and dyspnea. She had undergone a hysteroscopic resection for presumed uterine myoma one year prior, which was subsequently re-evaluated as LGESS. Multimodal imaging comprising 18F-FDG PET/CT, MRI, CT, and echocardiography was implemented for systemic staging and hemodynamic assessment, then revealed a solid uterine mass involving the adnexa (FIGO Stage IVB) and identified hypermetabolic tumor thrombi extending from the IVC into the right atrium and pulmonary arteries. A coordinated one-stage radical resection was performed, involving total hysterectomy and removal of intracardiac thrombi under cardiopulmonary bypass. Postoperative pathology and immunohistochemistry confirmed LGESS (CD10+, ER+, PR+) with extensive lymphovascular invasion. The patient recovered uneventfully with no residual disease on follow-up and commenced adjuvant letrozole therapy. This case highlights the necessity of multimodal imaging for accurate staging of complex vascular involvement and demonstrates that aggressive one-stage surgical management is a viable strategy to achieve locoregional control and favorable early outcomes for advanced LGESS with cardiac metastasis.