Two-stage resection of a disseminated mixed endometrial stromal sarcoma and smooth muscle tumor with intravascular and intracardiac extension.

Objective: Mixed endometrial stromal and smooth muscle tumor (MESSMT)-a rare mesenchymal uterine tumor of the uterus with atypical clinical symptoms-is susceptible to misdiagnosis and missed diagnosis. We report a case of a disseminated MESSMT with intravenous and intracardiac extensions treated with staging surgery and review previously documented cases of such tumors with intracardiac extension.

Case Report: The case involves a 45-year-old woman with disseminated MESSMT that originated in the uterus and progressed through the iliac vein, inferior vena cava, right atrium, and into the right ventricle, which closely resembled intravenous leiomyomatosis (IVL) grossly and microscopically. She presented with a 1-year history of dyspnea on exertion. IVL was highly suspected preoperatively based on computed tomography and magnetic resonance imaging findings. Two-stage surgeries were performed successfully. The postoperative pathology indicated a disseminated MESSMT.

Conclusion: This case illustrates the important role of pathology and immunohistochemistry in the differential diagnosis of a rare tumor that mimics the characteristics of IVL with intracardiac involvement and demonstrates the therapeutic strategy for this rare entity.