Introduction

Left atrial masses are uncommon and most frequently represent thrombi in patients with atrial fibrillation, mitral valve disease, or severe left atrial enlargement [1]. Giant mobile masses prolapsing through the mitral valve are particularly rare and present a high risk of systemic embolization and acute hemodynamic compromise [2].

Patients with cancer have an increased risk of intracardiac masses due not only to cancer-associated hypercoagulability but also to direct neoplastic intravascular extension [3,4]. Distinguishing between thrombotic and neoplastic lesions is clinically crucial, as therapeutic strategies and prognostic implications differ significantly. Imaging findings may overlap considerably, particularly in highly mobile intracardiac lesions [5].

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms characterized by the NAB2-STAT6 fusion gene and nuclear STAT6 expression on immunohistochemistry. Although initially described as pleural tumors, SFTs may arise in nearly any anatomical location and exhibit variable biological behavior, ranging from indolent lesions to highly aggressive metastatic malignancies [6,7]. Cardiac involvement by SFT is exceptionally rare.

Approximately 10%-20% of SFTs behave malignantly and may spread by local invasion, hematogenous dissemination, or direct intravascular extension through adjacent venous structures such as the pulmonary veins [7-9]. This mechanistic diversity, combined with the nonspecific echocardiographic appearance of intracavitary tumor extension, makes distinguishing neoplastic involvement from bland thrombus particularly challenging on imaging alone, as illustrated by the present case.

In patients with advanced malignancy, surgical management of intracardiac masses may be complicated by overall prognosis, making conservative approaches often preferable. However, giant highly mobile masses prolapsing through the mitral valve represent a surgical emergency because of the imminent risk of embolization or mechanical obstruction [2].

We report a case of a giant multilobulated left atrial neoplastic mass in a patient with metastatic malignant SFT, detailing the echocardiographic features, pathological findings, clinical decision-making, and therapeutic management.