Aneurysm of the right renal vein arising from an idiopathic arteriovenous fistula.

A renal vein aneurysm is rarely secondary to an arteriovenous fistula. A symptomatic 4.7-cm aneurysm of the right renal vein arising from an idiopathic arteriovenous fistula in a 41-year-old woman is described. Imaging techniques have a critical role in planning the treatment. The 4.7-cm aneurysm showed a venous wall with uneven thickening of the intima, irregular atrophy and architectural disarray of the media, and partial loss of elastic fibers. Potential for rupture supports surgical intervention in a selected patient with a macroaneurysm.