Aortic Pseudoaneurysm Mimicking a Pulmonary Neoplasm in an 87-Year-Old Patient: The Challenge of the "Great Mimicker" in Emergency Medicine.

Acute aortic syndrome (AAS) is a cardiovascular emergency associated with high mortality and often presents a diagnostic challenge, particularly in geriatric patients. We report the case of an 87-year-old woman who presented with acute chest pain, elevated biomarkers (troponin T and D-dimer), and an incidental finding on computed tomography (CT) of a mass in the left pulmonary apex. Initially suspected to represent a lung neoplasm because of associated constitutional symptoms, multidisciplinary review and dedicated aortic imaging subsequently revealed a pseudoaneurysm arising from a penetrating aortic ulcer of the distal aortic arch. The patient was successfully treated with straightforward thoracic endovascular aortic repair (TEVAR), without the need for supra-aortic branch coverage or adjunctive revascularization procedures, as the lesion was located distal to the origin of the supra-aortic branches. This case highlights the importance of considering AAS in the differential diagnosis of mediastinal and pulmonary masses in elderly patients.