Inflammatory aneurysm: a cause of obstructive nephropathy.

Inflammatory aortic aneurysms are aneurysms that are surrounded by a variable amount of periaortic fibrosis. This periaortic fibrosis may involve abdominal viscera, such as the duodenum, inferior vena cava, renal veins, or ureters, to a variable degree. On ultrasonographic images, the periaortic fibrosis appears as a hypoechoic mass surrounding the anterior and anterolateral aspects of a dilated aorta. Computed tomography scans reveal a periaortic mass of inflammatory tissue surrounding a dilated atherosclerotic and thickened aorta. The inflammatory mass may enhance to the same extent or slightly less than the aortic lumen following intravenous administration of a contrast agent. Magnetic resonance imaging scans may show the periaortic mass of inflammatory tissue to have a pseudocapsule of compressed fat at its periphery. Recognition of this entity and the extent of the inflammatory process is important to the definitive management of this condition, as illustrated by the case presented.