The patient is a healthy 46-year-old

man with no prior history of medical problems who developed the acute onset of left flank pain and gross hematuria 1 day after riding on a wooden roller coaster. He presented to the emergency room 6 days later for evaluation and was found to be anemic with a hemoglobin level of 6.7 and hematocrit level of 19. He was hemodynamically stable. Computed tomographic urogram demonstrated hyperattenuation in the left collecting system and a large clot in the bladder (Figure 1). On arterial phase, there was evidence of an enhancing 3-cm left lower pole renal mass. Magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) confirmed these Inhibitors,research,lifescience,medical findings (Figure 2). Cystoscopy and left ureteroscopy

revealed active bleeding from the left renal pelvis without a clear identifiable source. An arteriogram demonstrated a 22-mm pseudoaneurysm Inhibitors,research,lifescience,medical in the lower pole of the left kidney. This was coiled off selectively and the bleeding stopped immediately. Figure 1 (A) Computed tomographic Inhibitors,research,lifescience,medical urogram of the abdomen/pelvis demonstrated hyperattenuation in the left collecting system and (B) a large filling defect in the left renal pelvis and bladder suggestive of clot. Figure 2 Magnetic resonance imaging/magnetic resonance angiography of the abdomen/pelvis demonstrated enhancement of a left lower pole renal mass. Discussion Renal artery aneurysms (RAA) are localized dilations of the renal artery and/or branches. It was the first disease process of Inhibitors,research,lifescience,medical the

renal artery to be identified and has historically been considered a rare phenomenon until the widespread use of angiography.1 In 1957, 141 cases of RAA had been reported in the literature1 and by 1967, this number had risen to well over 300.2 A true aneurysm is a balloonlike dilation Inhibitors,research,lifescience,medical of all layers of the vessel wall, whereas a false (pseudo) aneurysm is derived from tissues surrounding the arteries.1,3,4 There are 4 basic structural types: saccular, fusiform, Smad2 signaling dissecting, and arteriovenous/microaneurysms.5 Saccular are the most common and represent 70% to 75% of all RAAs.1,4,5 Intraparenchymal RAAs are rare and account for < 10% of see more all RAAs.4,6 Although rare, there has been a recent increase in the discovery of renal arteriovenous fistulas secondary to trauma, inflammation, renal surgery, and percutaneous needle biopsy.7 Approximately 75% of renal arteriovenous fistulas are acquired and easily identifiable by their cirsoid configuration. 4 These aneurysms account for 17% of all RAAs and do have the tendency for rupture.4 The overall incidence of RAA in autopsy studies ranges from 0.01% to 0.3%1,5 and has even been reported to be as high as 9.7% in one autopsy study2; however, more recent literature has demonstrated that the overall incidence ranges between 0.01% to 1%.6,7 This increases to 2.