Right atrial thrombus-in-transit initially suspected as myxoma in a patient with acute pulmonary embolism: A case report

A 60-year-old man presented with sudden syncope, chest pain, and dyspnea. Transthoracic echocardiography at a local hospital suggested a right atrial myxoma, and he was referred for emergency treatment. On admission, markedly elevated D-dimer and cardiac troponin I levels were accompanied by severe hypoxemia. Intraoperative transesophageal echocardiography showed a large, highly mobile, cord-like right atrial mass without a definite pedicle. Because of the patient's critical condition, emergency surgical thrombectomy and pulmonary embolectomy under cardiopulmonary bypass were undertaken, revealing right atrial thrombus-in-transit with partial incarceration through the foramen ovale into the left atrium and extensive pulmonary emboli. Histopathological examination confirmed thrombus, and postoperative ultrasonography demonstrated deep venous thrombosis in the right lower extremity. The patient recovered well with anticoagulation. This case highlights that right atrial thrombus-in-transit may mimic myxoma on echocardiography and should be strongly suspected when a right atrial mass is accompanied by severe hypoxemia and other findings suggestive of acute pulmonary embolism.