Giant Iliac Artery Pseudoaneurysm Mimicking Postoperative Fluid Collection and Diskitis

In this report, we describe an extremely rare case of a giant pseudoaneurysm of the internal iliac artery causing marked destructive changes at a disk space and mimicking diskitis-osteomyelitis. Only 2 other cases of pseudoaneurysms extending into the disk space have been reported, and those arose from the aorta and were relatively straightforward to diagnose.

Our case is unique because the pseudoaneurysm arose from the internal iliac artery, an artery that is not usually included in the field of view of lumbar magnetic resonance imaging or computed tomography. However, the pseudoaneurysm was so large that it extended to the lumbosacral junction, where it eroded a disk space and caused findings of diskitis-osteomyelitis.

Complex paraspinal fluid collections causing osseous erosions should raise the possibility of an aneurysm/pseudoaneurysm. Computed tomography or conventional angiography should be considered if the question of a vascular mass/collection cannot be answered on conventional cross-sectional imaging, as inadvertent biopsy of a pseudoaneurysm can cause catastrophic bleeding.