An elderly man presented to the emergency department with a 1-month history of new-onset, persistent lower abdominal and flank pain. The pain was sharp and constant with intermittent radiation to the back and associated anorexia with a 10-kg weight loss. He did not report any previous abdominal surgery. The patient stated that he had not had any procedures with intravascular instrumentation in the past year, dental cleanings, intravenous drug use, cutaneous abscesses, or recent trauma. Physical examination revealed he was afebrile and in normal sinus rhythm; there was minimal epigastric abdominal tenderness without signs of peritonitis and no palpable masses. Femoral pulses were palpable and symmetric. Laboratory examination revealed mild anemia (hematocrit, 35% [to convert to a proportion of 1.0, multiply by 0.01]), no leukocytosis, and an elevated erythrocyte sedimentation rate (71 mm/h). Blood and urine cultures were negative for organisms. A computed tomographic (CT) angiogram showed asymmetric attenuation surrounding the infrarenal aorta (Figure 1). On comparison, a CT scan that was performed 6 months before presentation had identified no aneurysmal disease.