Variation in the histopathological features of patients with ascending aortic aneurysms: a study of 111 surgically excised cases

Background: Ascending aortic aneurysms ( AA) are a common, though poorly understood medical condition. Aims: To document the histological changes in a large series of human ascending AA, and to correlate these changes with clinical variables. Methods: 111 ascending AA were excised at surgery over a 3 year period. Each aneurysm was received as a continuous ring of tissue. Sections were taken from the anterior, posterior, greater and lesser curvature of the aorta and graded in a semi-quantitative fashion for the degree of elastin fragmentation, elastin loss, smooth muscle cell (SMC) loss, intimal changes and inflammation. Results: Mean patient age at surgery was 58.7 (15.6) years; there were 70 men and 41 women. 12 patients had Marfan syndrome, 34 (30.6%) had a bicuspid aortic valve (BAV), while 71 (64.0%) had a tricuspid aortic valve (TAV). Inflammatory cells were present in 28 cases (25.2%) and were confined to the adventitia. No particular region of the aortic circumference was more severely affected, however a BAV was associated with significantly less intimal change, and less fragmentation and loss of elastic tissue compared with patients with a TAV. Advanced age (. 65 years), female gender and Marfan syndrome were all associated with more severe elastin degeneration and smooth muscle cell loss ( p < 0.05 for all). Conclusion: Results indicate a wide variation in the histological appearance in ascending AA, depending on patient characteristics. They suggest that the underlying aneurysm pathogenesis may also be highly variable; this warrants further investigation.