[The so-called inflammatory aneurysm of the abdominal aorta]

The computer tomographic appearances of four patients with the rare inflammatory aneurysm of the abdominal aorta are described. The condition, whose aetiology is not known, affects mostly men in the fifth, sixth and seventh decade. Computed tomography shows, in addition to the typical changes due to an aortic aneurysm, horse-shoe shaped, circular, homogeneous peri-aneurysmal masses, which enhance after intravenous contrast. Bolus injection of contrast is necessary in order to differentiate these from a dissection or retroperitoneal lymphoma. Distinction between these conditions is possible as a result of the various types of enhancement which occur in the aortic lumen, in fibrosis and in lymphoma.