Renal artery aneurysms occur with a frequency of less than 1% of the general population. Even if they are usually asymptomatic and incidentally found, they can be complicated with life-threatening conditions like rupture, thrombosis, embolism, or hypertension. Thus, once diagnosed, they should be fully evaluated with further imaging and treated when indicated. We present the case of a patient who was referred for ultrasonography for an unrelated reason. The examination demonstrated a hyperechoic focus near the right kidney. Further imaging workup with MDCT established the diagnosis of a right renal artery aneurysm which was saccular in shape and peripherally calcified. This ring-like calcification was also visible in a KUB radiography which was also performed. After presenting the case, various aspects of this rare entity are discussed.
The term renal artery aneurysm (RAA) characterizes a focal dilatation of the renal artery or its branches. It can be discovered incidentally during workup for hypertension or during abdominal imaging for an unrelated reason (i.e., KUB radiography or ultrasonography) [
A 72-year-old man was referred to the Radiology Department by the Department of Urology for ultrasonography of kidneys, bladder, and prostate for dysuria. He denied history of trauma and his past medical history was free of hypertension or other diseases.
Ultrasonography revealed that the kidneys were normal except for some cortical cysts of the right kidney. Moreover, there was a hyperechoic focus with acoustic shadow adjacent to the pelvis of the right kidney. These findings were considered to represent a calcified structure of the renal pelvis (Figure
(a) This grey-scale transabdominal ultrasonography image of the right renal area was acquired with a curvilinear multifrequency transducer. It incidentally revealed a curvilinear reflective line with acoustic shadow behind it. This structure was located near the renal pelvis. (b) Color Doppler imaging demonstrated blood flow within the previously described structure. Thus, the structure should be vascular in its nature.
This KUB radiography showed a retroperitoneal curvilinear calcification with discontinuous border, which lied near the right transverse process of the second lumbar vertebra (arrow). This calcification correlated with the ultrasonographically detected pararenal vascular structure with wall calcification.
Finally, a contrast-enhanced MDCT examination was performed to fully evaluate the suspected RAA and establish the diagnosis. The examination demonstrated the presence of a saccular, peripherally calcified aneurysm of the right renal artery. The aneurysm’s diameter was 1.8 cm. After the intravenous administration of contrast medium, the aneurysm showed central enhancement and peripheral thrombus (Figures
Precontrast (a) and postcontrast (b) axial MDCT images. We can see that the ring-like calcification represented an aneurysm of the right renal artery which had a diameter of 1.8 cm and was saccular in shape.
(a) Curved reconstructed image along the right renal artery visualizing in a better way the saccular shape of the aneurysm and the central enhancement from the contrast flow within it. (b) 3D volume rendering technique image of the right renal artery demonstrating the detected aneurysm in an illustrative way and providing us with its detailed anatomy.
The term renal artery aneurysm (RAA) refers to the localized dilatation of the renal artery and/or its branches. The dilatation must be at least twofold in order to be considered an aneurysm [
RAAs usually cause no symptoms but can be complicated by important conditions like rupture, thrombosis, distal embolism, obstructive uropathy, hypertension of renovascular aetiology, and arteriovenous communications [
Imaging is necessary for establishing the diagnosis of an RAA. It has been reported that excretory urography is diagnostic or suggestive of an RAA in only 66% of the patients, whereas angiography poses the diagnosis in 100% of the patients [
In general, vascular lesions of the renal sinus like an RAA may initially appear as mass-like lesions. However, their vascular nature is easily identified with color Doppler ultrasonography, contrast-enhanced CT, MRI, and angiography. As more than half of the RAAs have a ring-like calcification, they must be differentiated from renal calculi. This is especially important when extracorporeal shock wave lithotripsy is to be performed [
As in our case, grey-scale ultrasonography and color Doppler ultrasonography can also raise suspicion of the existence of an RAA. Namely, the calcification of an RAA may be visualized as crescent-shaped echogenic foci with distal acoustic shadowing. The ultrasonographic differential diagnosis of a renal artery aneurysm includes a parapelvic cyst, hydronephrosis, or renal tumours. The usual ultrasonographic appearance of an RAA includes a fluid mass with flow characteristics with Doppler ultrasonography revealing turbulent flow within it. RAA can only rarely cause hydronephrosis as it is usually located in the main renal artery and its primary branches without obstructing the pyelocalyceal system. Finally, nuclear scintigraphy can also be suggestive of this condition [
RAA should be treated when causing haemorrhage or uncontrolled hypertension or when they are bigger than 2 to 2.5 cm or they progressively enlarge. Other indications for treatment comprise the presence of an arteriovenous fistula or an RAA greater than 1 cm in women of childbearing age [
RAA should be always included in the differential diagnosis of parapelvic, pararenal masses with rim-like calcification. Even though they can be asymptomatic and incidentally found, they should always be reported and fully investigated. Furthermore, they should always be followed up and under certain indications treated to avoid life-threatening complications.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Vasileios Rafailidis MD has received a scholarship for his postgraduate studies by Onassis Foundation.