[Intravenous leiomyomatosis with extension into the right atrium: differential diagnosis from right atrial myxoma by intraoperative transesophageal echocardiography].

: Intravenous leiomyomatosis (IVL) is an uncommon neoplasm characterized by the growth of a benign-looking smooth muscle tumor into the venous system. Intracardiac extension of this tumor is rare and may be misdiagnosed as right atrial myxoma unless the extracardiac part of the tumor is fully evaluated. We report a case of a 76-year-old woman whose preoperative diagnosis was right atrial myxoma. Intraoperative transesophageal echocardiography (TEE) revealed that the tumor had an extracardiac origin, resulting in tumor removal from the heart chamber and a part of the inferior vena cava (IVC) under circulatory arrest. When the findings of no attachment of the tumor to the interatrial septum or the right atrial wall and the tumor extension through the IVC are obtained by TEE examination, IVL should be considered as a differential diagnosis.