MSSA Thoracic Mycotic Aneurysm Repaired with TEVAR: A Case Report.

Background and Clinical Significance: Mycotic aortic aneurysm is a rare but life-threatening vascular condition characterized by infection-induced dilation or pseudoaneurysm formation in the aorta. The condition carries a high risk of rupture and mortality, especially in individuals with underlying cardiovascular disease, who have undergone recent vascular procedures, or with immunocompromising comorbidities such as diabetes. Its diagnosis is challenging due to its non-specific symptoms and often requires a high index of suspicion, especially in patients presenting with persistent fever and negative initial imaging. Early recognition and intervention are critical, as delayed treatment significantly worsens outcomes. Case Presentation: A 68-year-old male with a history of coronary artery disease, recent stent placement, and hypertension presented with two days of fever, chills, rigors, and a mild nonproductive cough. The laboratory findings were only significant for leukocytosis. The initial chest X-ray and non-contrast CT scans were unremarkable. He was admitted for presumed pneumonia and started on intravenous antibiotics. Persistent fever prompted further investigation with contrast-enhanced CT, which revealed a distal-aortic-arch pseudoaneurysm and mild mediastinal stranding. Blood cultures grew methicillin-sensitive Staphylococcus aureus (MSSA). Transthoracic echocardiogram was negative for endocarditis. The patient was transferred to a tertiary center, where repeat imaging confirmed a 1.5 cm pseudoaneurysm and a 4 mm penetrating atherosclerotic ulcer. After multidisciplinary assessment, he underwent thoracic endovascular aortic repair (TEVAR) and completed four weeks of intravenous cefazolin. Follow-up imaging showed successful aneurysm repair with no complications. Conclusions: Thoracic mycotic aneurysm is a rapidly fatal entity despite intervention. High clinical suspicion is necessary given its non-specific presentation. It is diagnosed most practically using CTA. In addition to antibiotics, TEVAR is gaining traction as a feasible and a safe alternative to open surgical repair (OSR).