Right atrial masses with suspicion of malignancy: a multicentre cohort study

Right atrial (RA) masses are uncommon but clinically significant findings, encompassing a broad spectrum of aetiologies spanning from vestigial tissue (non-pathologic) to metastatic disease. The diagnosis is challenging, and misclassification may lead to inappropriate management. Multimodality imaging plays a central role in differentiating malignant from non-malignant lesions, guiding treatment strategies. To characterise the diagnostic pathways, management strategies, and clinical outcomes of patients referred with RA masses suspicious for malignancy, and to evaluate the role of multimodality imaging in diagnostic classification. This multicentre retrospective study included patients referred for suspected malignant RA masses from three tertiary centres between 2011 and 2025. Imaging modalities, histological data, treatments, and outcomes were analysed. Patients were classified into diagnostic groups based on final diagnosis. Fifty-four patients were referred with suspected right atrial (RA) masses. Demographic characteristics of the population are summarized in table 1. A definitive diagnosis was established in 50 patients, who were classified into four groups (table 2): thrombus (n = 23), benign masses (n = 14), metastatic masses (n = 8), and primary malignant masses (n = 5). Four cases were non-diagnostic. Transthoracic echocardiography (TTE) was performed in all patients (100%) as first-line imaging. Due to diagnostic uncertainty, advanced imaging was frequently required, with cardiac magnetic resonance (CMR) performed in 23 patients (42.6%) and PET/PET–CT in 13 patients (24%). Histological confirmation was obtained in 10 patients (18.5%). All patients with RA thrombus were treated with anticoagulation alone (100%). Benign masses were mainly managed conservatively, with surgery in 21.4% and anticoagulation in 14.2%. In the metastatic group, treatment was primarily with chemotherapy in 37.5%, and surgery in 12.5%; 25% were managed palliatively. All patients with primary malignant masses received chemotherapy (100%), and 40% also underwent surgery, reflecting a multimodal approach. Prognosis was directly related to the final diagnosis: mortality was 21.7% in thrombus, 14.2% in benign masses, 25% in metastatic disease, and 80% in primary malignant tumours. Primary malignant masses were predominantly sarcomas, while over half of thrombi were catheter-related, highlighting distinct biological behaviour and risk. RA masses represent biologically distinct entities with different pathways, management strategies, and prognoses. Multimodality imaging is essential for accurate classification, particularly to differentiate thrombus from malignancy. Early and precise diagnosis is the key determinant of appropriate treatment selection and clinical outcome, with primary malignant RA tumours carrying a particularly poor prognosis.