Histopathological evaluation of aortic dissection: a comparison of congenital versus acquired aortic wall weakness

The aim of this study was to identify pathological changes of aortic dissection based on histopathological evaluation of aortic wall weakness by comparing patients with and without congenital abnormalities.

We reviewed records of patients who underwent repair for dissection-related aortic disease between 2008 and 2015. Fifty patients (20 men and 30 women; mean age 66.9 ± 14.0 years) who underwent surgery with subsequent histopathological examination of the aortic wall were divided into 2 groups. Group 1 had congenital abnormalities, including Marfan syndrome and bicuspid aortic valve (n = 5), and Group 2 had no congenital abnormalities (n = 45). We compared the histopathological characteristics of the aortic wall in these patients.

There were significant differences in age and body surface area between the 2 groups. Although 80% of Group 1 patients developed dissection at the middle of the media, all Group 2 patients developed dissection at the outer one-third of the media, which is along the pathway of the vasa vasorum of the aortic wall. Both groups showed the same extent of degeneration of the vasa vasorum. Group 1 showed a severe score of mucoid extracellular matrix accumulation in the aortic media.

Although it may be multifactorial, congenital maldevelopment of the media tends to result in dissection of the centre of the media, and acquired aortic wall weakness is concentrated in the outer third of the media. Degeneration of the vasa vasorum may be an important emerging substrate for developing aortic dissection.