Misdiagnosed right atrial tumor identified by intraoperative transesophageal echocardiography.

A 16-year-old male patient was referred to our institution due to occasional chest tightness for one month. Electrocardiogram showed some atrioventricular junctional beats. Transthoracic echocardiography revealed a hyperechoic mass about 1.4 × 0.5 cm in size in the right atrium. He was then scheduled for operation under the impression of possible right atrial myxoma. After general anesthesia, a transesophageal echocardiography (TEE) examination revealed a serpentine, highly mobile echocardiographic structure with focal thickening within the right atrium (Fig. 1). The curvilinear right atrial echoes originated from coronary sinus and were attached to the right atrial wall (Fig. 2). The hyperechoic target did not obstruct right ventricular inflow. There was only mild tricuspid regurgitation. A prominent Chiari network was then diagnosed. The operation was cancelled. Subsequently, the patient was regularly followed in outpatient clinics. The valve of the sinus venosus at an early stage of embryonic development nearly divides the right atrium into two chambers and it normally disappears early in fetal life. When there is extensive resorption of the right sinus venosus valve,