Vertebral body erosion secondary to aortoiliac aneurysm.

A 75-year old female patient presenting chronic arterial hypertension, was admitted at the emergency department with moderate unspecific abdominal pain. A computed tomography of total abdomen with no contrast enhancement was requested due to altered renal function and suspicion of acute obstructive abdomen.

The computed tomography sections (Figures 1 and 2) showed a fusiform aneurysm in the aortoiliac bifurcation, extending up to the right iliac artery. This aneurysm was causing erosion of the anterior aspect of L4 vertebral body, with bone remodeling, marked by subjacent cortical sclerosis.

Figure 1

Axial computed tomography image of total abdomen with no contrast enhancement shows aortoiliac aneurysm with peripheral calcifications (red arrow), causing erosion of the anterior aspect of L4 vertebral body (green arrow)

Figure 2

Sagittal computed tomography reconstruction shows the aortoiliac aneurysm is in continuity with abdominal aorta (red arrow), as well as erosion and bone remodeling of the anterior aspect of L4 vertebral body (green arrow)

Vertebral collapse and lytic lesions are usually related to fractures, tumors, osteoporosis, spondylitis or spondylodiscitis. Nonetheless, the erosion in the anterior aspect of the vertebral body can also result from an abdominal aorta aneurysm, or even mimick tumors or infections.( , )

A computed tomography finding suggestive of an impending rupture of an abdominal aorta aneurysm is the draped aorta sign, which refers to the loss of fat plan that separates the aorta from the anterior aspect of the spine and psoas muscle. Erosion of the anterior aspect of vertebral body, as observed in this case, is the most exuberant manifestation of this sign. The mechanism suggested in this context is repetitive mechanical pressure by arterial pulsation, which would cause chronic ischemia in the bone matrix, leading to bone lysis and remodeling.( – ) Preservation of the disk spaces decreases the risk of infection and helps in making differential diagnosis. This finding indicates an imminent risk of rupture, which must be promptly identified. The attending physician of the patient should be informed about this risk, considering the mortality rates after complete rupture are approximately 90%.( )

Therefore, radiologists should be familiarized with such images indicating an impeding risk of rupture of abdominal aorta aneurysm, even in non-contrast enhancement exams.( , )