Inflammatory aneurysm of the abdominal aorta. A prospective clinical study

This study was undertaken to investigate a consecutive series of abdominal aortic aneurysm studied with histology to highlight the etiology, the incidence, the value of preoperative studies and intraoperative findings.

Prospective study.

University hospital.

Between 1992 and 1994, 102 patients underwent elective surgical repair of an abdominal aortic aneurysm. The patients were prospectively divided as having an inflammatory aneurysm (IA) or an atherosclerotic aneurysm (AA) on the basis of preoperative and intraoperative findings. Further histological evaluation assigned the patients to one of the two groups.

The incidence of IA was 15%. Overall, symptoms, CT scan studies, aneurysmal wall thickness, white glistening perianeurysmal fibrosis, bleeding from the aneurysmal wall and adhesion to the duodenum diagnosed 11 (73%) cases of IA. Histology showed that a granulomatous reaction against some components of the atherosclerotic plaques resulting in an auto-allergic response to this component could initiate the inflammatory process thus resulting in a progressive adventitial and peri-adventitial fibrosis with inflammation, lymphadenitis and lymphatic dilatation.

Preoperative and intraoperative findings underestimate the incidence of IA. Aortic resection can prevent the progression of the inflammatory process and the complications usually observed when the exposure to the allergen determines an involvement of the periaortic structures.