Inflammatory abdominal aortic aneurysm: report of six cases.

Six cases of inflammatory aneurysm of the abdominal aorta are described. All patients were male, aged 59 to 80 years, and five had symptomatic atherosclerotic cerebrovascular or cardiovascular disease. In three the diagnosis of inflammatory aneurysm was suggested preoperatively on the basis of computed tomographic or ultrasonographic scanning. On gross examination the aneurysm wall was about 1 cm thick and included an inner narrow layer of atherosclerotic plaque, which was contiguous with the outer thick fibroinflammatory component. Microscopically, this component consisted of fibroblasts and collagen, which entrapped fat, nerves, and lymph nodes and was infiltrated by lymphocytes and plasma cells. Plasma cells, lymphocytes, and fibroblasts predominated in four patients, while two showed abundant dense collagen with fewer inflammatory cells and fibroblasts. There was associated vasculitis, predominantly phlebitis, in three. Inflammatory aneurysms represent a distinct group of abdominal aortic aneurysms.