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

Right atrial thrombi are rare findings observed on echocardiography. This case illustrates an incidental spherical thrombus located near the inferior vena cava entrance at the top of the right atrium. The echocardiographic features of this thrombus can resemble those of a myxoma, necessitating careful differentiation through additional examinations. In this case, the misdiagnosis on TEE was attributed to the mass displaying slightly increased echogenicity, a narrow attachment to the right atrium near the inferior vena cava, and a degree of mobility. Typically, thrombi appear hypoechoic; however, the slightly elevated echogenicity observed here may be due to the chronicity of thrombus formation, which could also account for the narrow attachment. According to the PLACE-T scoring system, the following points were assigned:P (Patient history): 0 points.L (Lobulation): Lobulated contour, 0 points.Attachment site width: Narrow stalk (base diameter/maximal diameter <0.3), +2 points.Clinical context: No relevant medical history, 0 points.Echogenicity pattern: Heterogeneous echogenicity, +1 point.T (Tissue characterization): No specific features, 0 points.With a total score of 3 points, the probability of a thrombus is high (sensitivity 92% and specificity 85% for scores ≤3). When TEE is not feasible or yields uncertain findings, other non-invasive imaging modalities such as multi-slice spiral CT (MDCT) or cardiac magnetic resonance imaging (CMR) may be considered. Although these techniques are predominantly used for left atrial assessment-MDCT, for instance, can successfully identify left atrial thrombus with a negative predictive value of 100% and a positive predictive value ranging from 41% to 92%-the accuracy of differentiating right atrial masses remains uncertain. Therefore, in similar cases, it is imperative to integrate the patient's clinical history, multiple auxiliary examination results, and the PLACE-T score rather than relying solely on the features observed on TEE.