Histological characteristics of the abdominal aortic wall in patients with vascular chronic Q fever

Abstract

The aim of this study was to describe specific histological findings of the Coxiella burnetii-infected aneurysmal abdominal aortic wall. Tissue samples of the aneurysmal abdominal aortic wall from seven patients with chronic Q fever and 15 patients without evidence of Q fever infection were analysed and compared. Chronic Q fever was diagnosed using serology and tissue PCR analysis. Histological sections were stained using haematoxylin and eosin staining, Elastica van Gieson staining and immunohistochemical staining for macrophages (CD68), T lymphocytes (CD3), T lymphocyte subsets (CD4 and CD8) and B lymphocytes (CD20). Samples were scored by one pathologist, blinded for Q fever status, using a standard score form. Seven tissue samples from patients with chronic Q fever and 15 tissue samples from patients without Q fever were collected. Four of seven chronic Q fever samples showed a necrotizing granulomatous response of the vascular wall, which was characterized by necrotic core of the arteriosclerotic plaque (P = 0.005) and a presence of high numbers of macrophages in the adventitia (P = 0.007) distributed in typical palisading formation (P = 0.005) and surrounded by the presence of high numbers of T lymphocytes located diffusely in media and adventitia. Necrotizing granulomas are a histological finding in the C. burnetii-infected aneurysmal abdominal aortic wall. Chronic Q fever should be included in the list of infectious diseases with necrotizing granulomatous response, such as tuberculosis, cat scratch disease and syphilis.

Keywords: aneurysm; chronic Q fever; granulomatous disease; infection; vascular disease.

Figure 1

Haematoxylin and eosin staining of the aneurysmal abdominal aortic wall of a chronic Q fever patient displaying a giant cell in a necrotizing granuloma.

Figure 2

Immunohistochemical staining for CD68 of the aneurysmal abdominal aortic wall of a chronic Q fever patient displaying characteristic palisading line up of macrophages (a) and the negative control sample. (b) An overview (1) and a magnified illustration (2) are given. A positive control sample for CD68 staining (3) is added (contains tissue of appendix).

Figure 3

Immunohistochemical staining for CD3 of the aneurysmal abdominal aortic wall of a chronic Q fever patient displaying diffuse accentuation of T lymphocytes in the media and adventitia: an overview (1) and a magnified illustration (2). Additionally, an image of the negative control sample (same patient) is added (3).