Anterior vertebral body erosion due to pressure from contained rupture of an abdominal aortic aneurysm

Clinical History

A 75-year-old woman with a history of hyponatraemia, weight loss and smoking underwent CT of the chest, abdomen and pelvis to investigate suspected malignancy as a chest radiograph demonstrated suspicious nodular opacities.

Imaging Findings

A huge low-density retroperitoneal mass measuring at least 74mm x 121mm x 100mm was identified, centred at the L4 level. It was eroding the L3, L4 and L5 anterior vertebral bodies and was closely associated with the posterior wall of the abdominal aorta. The lesion had a thin calcified rim which was in continuity with the aorta but it did not demonstrate contrast enhancement.

Discussion

This case of a contained rupture of an abdominal aortic aneurysm was found incidentally on a CT investigating suspected malignancy. Despite the volume of the thrombus adjacent to the rupture and associated anterior vertebral erosion, the patient remained asymptomatic.

The case was referred to the vascular multidisciplinary team for assessment where the findings were felt to be classical of a contained abdominal aortic aneurysm rupture and the best treatment option was believed to be conservative management.

Chronic contained rupture of abdominal aortic aneurysm are generally uncommon and can persist for long periods in asymptomatic patients [1]. Associated vertebral body erosion is however an even rarer occurrence [2]. The mechanism believed to be responsible for the erosion includes an inflammatory reaction secondary to chronic posterior aortic wall fissuring and mechanical barotrauma due to pulsation of the contained rupture [2].

Further characterisation has been performed with MRI [3] which demonstrated homogeneous low signal on T2 weighted imaging, slightly high T1 weighted signal and intravenous gadolinium enhancement of the rim but not the centre of the mass.

It is worth noting, while abdominal aortic aneurysms can present with back and leg pain [3], this case demonstrates that even complicated aneurysms with rupture and vertebral erosion can be asymptomatic. The absence of associated clinical deterioration suggested that the rupture was chronic and contained, therefore avoiding the need for invasive treatment in this case.

Differential Diagnosis List

Final Diagnosis

Anterior vertebral body erosion due to pressure from contained rupture of an abdominal aortic aneurysm

URL:	https://www.eurorad.org/case/13247
DOI:	10.1594/EURORAD/CASE.13247
ISSN:	1563-4086