Case Report: Neonatal Right Atrial Mass of Uncertain Etiology

Libor Svoboda^1*Sabine Mank²Sabine Meier³Marcel Vollroth³Alexandra Kiess⁴Christian Schürer¹

• ¹Department of Pediatric and Adolescent Medicine, University Hospital Jena, Jena, Germany
• ²Section of Pediatric Radiology, Department of Radiology, University Hospital Jena, Jena, Germany
• ³Department for Pediatric and Congenital Cardiac Surgery, Leipzig Heart Center, Leipzig, Lower Saxony, Germany
• ⁴Department of Pediatric and Adolescent Medicine,, University Hospital Jena, Jena, Germany

Neonatal intracardiac masses are rare and pose significant diagnostic and therapeutic challenges, particularly in differentiating thrombi from tumors. We present the case of a preterm neonate with a right atrial mass of uncertain etiology. Multimodal imaging, including echocardiography and cardiac MRI, suggested the presence of a thrombusconsistent with thrombi being the most common type of intracavitary cardiac mass. As a result, primary anticoagulation therapy was initiated. However, after 16 days without significant change in the mass and given the high risk of embolization and the possibility of a benign tumor, surgical excision was performed. Histopathological analysis of the excised tissue could not definitively distinguish between an organized thrombus and a regressed benign neoplasm, although no malignant cells were identified. This case highlights the diagnostic uncertainty surrounding neonatal intracardiac masses and the limitations of imaging and pathology in achieving definitive diagnosis. A multidisciplinary approach and long-term follow-up are essential, particularly when the true nature of the mass remains unclear.