LAUSR

A 69-year-old male presented to the vascular surgery clinic with a 4-month history of low back pain. His previous medical history was unremarkable except for a smoking habit (100 pack-years). The patient had undergone a computed tomography (CT) scan illustrating a 4-cm diameter infrarenal abdominal aortic aneurysm (AAA) and a large soft tissue mass between the abdominal aorta and the lumbar spine, eroding the L3 and L4 vertebrae (Panel A: axial view at the level of lumbar spine 4). Magnetic resonance imaging (MRI) documented the same features and suggested a mesenchymal lesion of neurogenic origin as the most likely diagnosis. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) revealed increased uptake in the peripheral rim of the mass with central sparing, indicative of malignancy with central necrosis or infection (Panel B). However, a fine-needle aspiration was negative for malignancy. The diagnosis of infection was rejected since the intervertebral disks were preserved. Subsequent computed tomography angiography (CTA) of the abdominal aorta displayed extravasation of contrast media within the ‘soft tissue mass’ (Panel C: axial view at the level of lumbar spine 4). Thus, the diagnosis of chronic contained rupture of an AAA with vertebral erosion was unequivocally made. An elective AAA open repair followed where a 3-cm diameter hole in the posterior wall of the aneurysm was found, through which the eroded vertebrae could be seen after removal of the clot (Panel D). Specimens of the retroperitoneal hematoma and the vertebral body were negative for infection or malignancy.