**3. Epidemiology**

Penetrating aortic ulcers comprise 2% to 11% of acute aortic syndromes [10]. In a classic autopsy study, only 4.6% of aortic dissections were found to originate from penetrating aortic ulcers [11]. In one study of incidental findings during cardiac computed tomography for acute chest pain in an emergency department setting, only 1 (0.3%) of 395 consecutive patients was found to have a penetrating aortic ulcer [12]. Another study of incidental findings during cardiac computed tomography similarly found a low prevalence of penetrating aortic ulcers, with only 2 (0.2%) detected in a sample of 966 patients [13].
