Introduction/Background Intravenous leiomyomatosis (IVL) is defined by the presence of smooth muscle nodules beyond the vessels of an uterine leiomyoma and into the extrauterine venous system. Its extension into the right-sided cardiac chambers can be fatal. Most cases lack marked nuclear atypia or elevated mitotic activity. Transition from a non-invasive leiomyoma to an invasive IVL is not clearly understood. The objective is to report a patient with intracardiac IVL with malignant histological features consistent with sarcoma.

Methodology 63 year old female, hemodynamically stable, referring a painful mass that occupied the pelvic cavity up to the hypogastrium, associated to abnormal uterine bleeding. Abdominal-pelvic magnetic resonance image (MRI) reported a solid tumor originating in the posterior wall of the uterus, and a solid tumor that extended through the right external iliac vein up to the right atrium (RA) partially occupying the inferior vena cava (IVC) and the right common iliac vein. Chest computed tomography showed no pulmonary metastasis. Cardiac MRI reported an intravascular thrombus of tumoral origin that extended from the IVF to the RA protruding through the tricuspid valve (TV) into the right ventricule (RV). Tran-sesophageal echocardiography revealed a 37x13 mm vascularized irregular mass extending from the IVC into the RA going through the TV into the RV, with no effect on valvular function.

Results A one stage procedure was performed including pelvic tumor resection, hysterectomy, adnexectomy, dissection of the IVC with removal of the endovascular tumor and removal of the intracardiac tumor. Due to nonsurgical bleeding, a mediastinal packing was necessary with posterior unpacking 24 hours later. Final pathology examination reported a high grade sarcomatous malignant tumor within the pelvic mass and histological findings consistent with IVL.

Conclusion IVL has a quasi-malignant behavior. Complete tumor removal impacts prognosis and recurrence rates. Reports on IVL with malignant histological features are scarce.