Histological features of human abdominal aortic aneurysm are not related to clinical characteristics

Background: Clinical presentation, maximal aortic diameter (Dmax), and growth rate are considered important clinical characteristics of the abdominal aortic aneurysm (AAA). Histologically, AAA is characterized by pathological changes of the media. In the present study, we investigated whether and how the histological features of AAA were related to clinical characteristics. Methods: Clinical characteristics and anterior aneurysm wall biopsies were collected prospectively. Histological characteristics were determined by immunohistochemistry and morphometric analysis. Results: Thirty-nine consecutive patients with elective or emergency aneurysm repair were included. AAA was located infra- or juxtarenal in 77% and 23%, respectively. Mean maximal aortic diameter was 67 mm with a mean growth rate of 6 mm/year. The histological features included a low elastin content, distorted elastin configuration, high collagen content, diminutive number of smooth muscle cells, and a high number of medial microvessels and inflammatory cells dominated by T cells. However, no intra- or interrelationship between histological and clinical characteristics was present. In particular, Dmax and clinical presentation were not related to media thickness or inflammatory cell count. Conclusions: We conclude that histologically AAA Could not be classified in analogy to clinical characteristics. We Suggest that progression of large AAA is mainly determined by parameters other than histological features of the diseased vessel wall. (C) 2009 Elsevier Inc. All rights reserved.