A case report of a spherical mass in the right atrium: myxoma or thrombus?

Yulian Wu ¹ Xidan Wang ¹ Daoling Yang ¹ Xiaoying Tao ^1,2*

• ¹ Department of Ultrasound,JinHua Municipal Central Hospital, Jinhua 321000, Zhejiang,China, jinhua, China
• ² Jinhua Central Hospital, Jinhua, China

Intracardiac masses include tumors, thrombi, and other proliferative lesions. While the left atrium is more frequently involved, right atrial masses are relatively uncommon, and spherical thrombi in the right atrium are exceedingly rare. Diagnostic assessment typically relies on transesophageal echocardiography (TEE), cardiac magnetic resonance imaging (CMR), and multidetector computed tomography (MDCT). TEE offers detailed insights into a mass’s location, size, and mobility, whereas CMR and MDCT provide tissue characterization.We present the case of a 59-year-old male with no significant medical history aside from childhood lower extremity trauma. During a routine evaluation, a spherical mass was discovered in his right atrium. Initial TEE, including three-dimensional imaging, revealed a hyperechoic lesion with a thin stalk attached to the interatrial septum near the inferior vena cava, initially suggesting a myxoma. However, surgical resection and histopathological examination confirmed a thrombus, highlighting the potential for misdiagnosis when relying solely on standard imaging techniques.In this instance, the slightly elevated echogenicity of the mass, its narrow attachment, and some mobility on TEE contributed to the misinterpretation. Generally, thrombi appear hypoechoic, but chronic thrombus formation can increase echogenicity and produce a more defined stalk. The PLACE-T scoring system helped differentiate the lesion from a tumor. The patient scored three points (narrow stalk +2, heterogeneous echogenicity +1, and other factors 0), indicating a high likelihood of a thrombus (sensitivity 92% and specificity 85% for scores ≤3).When TEE findings are unclear or not feasible, additional non-invasive imaging such as MDCT or CMR can be employed. Though these modalities are primarily used for left atrial lesions, they may help clarify ambiguous cases in the right atrium. MDCT, for example, can reliably detect left atrial thrombi, but its accuracy for right atrial masses is less well established. Consequently, clinicians must integrate the patient’s clinical background, imaging results from multiple modalities, and objective scoring systems rather than relying solely on TEE features to prevent overlooking a possible right atrial thrombus.