Superior mesenteric artery syndrome caused by huge mycotic abdominal aortic aneurysm.

A 92-year-old man who had been hospitalized for dementia developed sudden-onset bilious vomiting accompanied by a fever of 40 degrees C. Physical examination revealed an 8 cm diameter pulsatile mass in the upper abdomen. Computed tomography of the abdomen demonstrated a huge infrarenal saccular aneurysm with a lobulated appearance. We considered this to be a mycotic abdominal aortic aneurysm compressing the third portion of the duodenum and causing proximal duodenal dilatation and superior mesenteric artery (SMA) syndrome.