Abstract: Mycotic pseudoaneurysm of the ascending aorta is extremely uncommon, particularly in children with no prior cardiac surgery or trauma. We report a rare case of a mycotic pseudoaneurysm of the ascending aorta in a 2-year-old girl with no history of cardiac surgery. Investigations revealed a methicillin-resistant Staphylococcus aureus infection and significant pericardial effusion in the child who presented with persistent fever and altered mental state. Cardiac ultrasound revealed a disruption in the aortic wall and a tumor-like structure. Contrast-enhanced computed tomography confirmed an ascending aortic pseudoaneurysm with thrombus. The child underwent successful surgical treatment without implants. This case emphasizes the diagnostic significance of imaging, particularly the advantages of ultrasound in pediatric settings, and the need for timely and accurate diagnosis using appropriate imaging modalities in children.

Keywords: aorta, mycotic, pseudoaneurysm