Mycotic aneurysm with aortoduodenal fistula.

Firstly described in the 19th century by Sir William Osler, the mycotic aneurysm (MA) is a rare entity characterized by an abnormal arterial dilation, which is potentially fatal, and is associated with the infection of the vascular wall. Elderly patients are mostly involved, especially when risk factors like chronic diseases, immunosuppression, neoplasia, and arterial manipulation are associated. The authors report the case of a young male patient diagnosed with an aortic aneurysm of infectious origin in the presence of repeated negative blood cultures.