Giant mass but small symptoms; huge thrombosis in the right atrium originating from the superior vena cava and protruding to the right ventricle: a case report.

Background: Thrombosis of the superior vena cava with propagation to the right heart chambers can be seen in the presence of chronic indwelling catheters. Moreover, the idiopathic right atrial thrombi may become entrapped in Chiari's networks, and idiopathic thrombosis of the superior vena cava may occur rarely because of the underlying coagulation disorders or malignancies.

Case Presentation: A 43-year-old Iranian (Persian) woman was admitted to our hospital with palpitation of 2 years' duration and mild to moderate dyspnea of 10 days' duration. Her past medical history, basic laboratory test results, and cardiac enzyme measurements were unremarkable. Imaging studies revealed a 1.4-cm × 7.4-cm multilobulated, hypermobile mass in the right atrium, extending into the right ventricle, that appeared to be emanating from the superior vena cava. Moreover, partial filling defects were visible in the distal parts of both right and left pulmonary arteries extending to their branches, suggesting massive pulmonary emboli. The patient's huge mass and emboli were removed by surgery, and pathologic evaluations confirmed that all of the specimens were thrombosis. A number of mutations known as risk factors of thrombosis were detected during genetic evaluations. However, mild symptoms of the patient along with a huge mass in the right atrium, thrombosis in the superior vena cava, and massive thromboembolism remained unexplained.

Conclusion: Huge and dangerous thrombosis inside the heart and superior vena cava can evolve without expected considerable symptoms. Also, detecting the underlying causes of these thromboses sometimes is not feasible by only checking the prevalent known risk factors. Therefore, comprehensive evaluations should be carried out in these patients.