Intravenous leiomyomatosis: a rare cause of intracardiac mass.

Intravenous leiomyomatosis is an unusual clinical condition characterized by histologically benign smooth muscle lesions extending from the uterus into pelvic and systemic veins and, more rarely, into the right cardiac chambers. We report the case of a 45-year-old woman who presented with a three-week history of dyspnea on exertion, shortness of breath and fatigue. Echocardiography showed a large mobile mass in the right atrium prolapsing into the right ventricle and extending to the inferior vena cava. A computed tomography scan revealed a large mass extending from the right atrium to the inferior vena cava and through the systemic veins as far as the popliteal veins. A presumptive diagnosis of large thrombus was made; the correct diagnosis of intravenous leiomyomatosis with intracardiac involvement was obtained only after surgical resection and histologic examination.