Intimal sarcoma of the heart and great vessels: clinicopathologic series with imaging and immunohistochemistry correlation.

Intimal sarcoma (IS) is an extremely rare but aggressive malignant tumor and is now recognized as the most frequent primary malignancy of the heart and great vessels. Its clinical presentation is often non-specific, frequently mimicking common conditions such as pulmonary embolism or cardiac myxoma, leading to significant diagnostic delays. This case series describes four women with IS in various locations: two in the left atrium with mitral valve involvement, one in the main pulmonary artery, and one presenting as a pulmonary mass. Diagnosis relied on multimodal imaging, including echocardiography, computed tomography, and magnetic resonance imaging, followed by histopathological confirmation. Microscopic analysis revealed marked cellular pleomorphism and high mitotic activity. Immunohistochemistry (IHC) was essential for the final diagnosis, as all cases demonstrated nuclear mouse double minute 2 (MDM2) expression, a defining marker associated with gene amplification. Other markers, such as h-caldesmon and diffuse cluster of differentiation 31, were negative, effectively excluding leiomyosarcoma and angiosarcoma. Given its poor prognosis and high embolic potential, early recognition and radical surgical resection remain crucial for patient survival. This series emphasizes the clinical relevance of considering IS in the differential diagnosis of intracardiac and endovascular masses, highlighting MDM2 IHC as a reliable diagnostic tool.