A Case of Syncope Due to Intracardiac Leiomyomatosis.

We present a case of a 46-year-old female presenting with syncope. Echocardiography initially showed a right atrial mass. Further evaluation revealed a mass arising from the fundus of the uterus, with a tumor thrombus in the left gonadal vein, extending into the left renal vein and through the inferior vena cava (IVC) into the right heart across the tricuspid valve. She was managed with surgical resection, and postoperative pathology was consistent with intravenous leiomyomatosis (IVL). IVL is a rare uterine smooth muscle cell neoplasm which extends into the venous system. Gynecological tumors are often overlooked in differential diagnosis for atrial masses. A benign tumor like fibroid, in rare circumstances, can extend into the right side of the heart causing dynamic obstruction to outflow tract, thus increasing mortality. The objective of this article is to present such a case and highlight the broad differentials of atrial masses, including IVL.