Aneurysm of proximal descending thoracic aorta on X-ray chest PA view and CT scan

Aneurysm of proximal descending thoracic aorta on X-ray chest PA view and CT scan

The saccular aortic aneurysm of the proximal descending thoracic aorta is visible within the cardiac silhouette just below the aortic knuckle on the left border. It is partly overlapped by the main pulmonary artery shadow. The cardiac size is normal and so is the ascending aorta. The findings on this chest X-ray are quite subtle so as to be missed by a casual examination. Similar findings may sometimes be noted in the elderly with atherosclerotic changes in the aorta without much aneurysmal dilatation.

CT scan demonstrates the aneurysm very well. The wall of the aneurysm is partly calcified. The aneurysm measured about 5.5 cm and was saccular. There was a past history of major trauma several years back producing multiple fractures.

Saccular aneurysms in general have a higher risk of rupture than fusiform aneurysms. Causes for saccular aneurysms of aorta include infections like tuberculosis and syphilis, progression of a penetrating atherosclerotic ulcer, prior trauma or aortic surgery, Behcet disease and Takayasu arteritis [1]. In the case illustrated here, remote trauma could have a causative role.

A retrospective study using a radiology database from 2003 to 2011 identified 322 saccular aortic aneurysms in 284 patients [2]. 219 of these were in the descending thoracic aorta as in the case illustrated here. 11 patients had ruptured saccular aortic aneurysms on the initial scan. Mean aneurysm growth rate was 2.8 mm per year in the study. Predictors of increased growth by multivariate analysis were decreased calcium burden and increased patient age in that study.

References

1. Preventza O, Coselli JS. Saccular Aneurysms of the Transverse Aortic Arch: Treatment Options Available in the Endovascular Era Based on a Presentation at the 2013 VEITH Symposium, November 19-23, 2013 (New York, NY, USA). Aorta (Stamford). 2015 Apr 1;3(2):61-6.
2. Shang EK, Nathan DP, Boonn WW, Lys-Dobradin IA, Fairman RM, Woo EY, Wang GJ, Jackson BM. A modern experience with saccular aortic aneurysms. J Vasc Surg. 2013 Jan;57(1):84-8.