SONOWORLD : Right renal cell carcinoma
 
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Right renal cell carcinoma; Incidental finding of saccular aneurysm of the right renal artery
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Presentation A 64 year old male presented in the Clinical Institute of Urology and Renal Transplantation for urinary urgency and asymptomatic right renal mass discovered incidentally during an ultrasonographic exam for gallstones. Blood tests were normal. Intravenous pyelography showed a 3cm mass bulging from the lower pole of the right kidney, with increased parenchymal thickness. Abdominal ultrasound was performed to assess the renal morphology.
 
 
 
Caption: CT, nonenhanced axial scan through the right kidney
Description: Left: A rounded mass, measuring 2.1/1.4cm, with wall calcifications is seen along the right renal artery course. Right: The wall calcifications of the mass are better depicted.
 
 
 
Caption: CT, post-contrast axial scan through the kidneys
Description: A tumoral mass measuring 5.2/5.2cm, with peripherical enhancement and hypodense center is observed in the inferior third of the right kidney. The rounded mass located along the right renal artery course presents arterial phase increased density.
 
 
 
Caption: Macroscopic and microscopic pathology images
Description: Left: macroscopic image of the renal cell carcinoma: a tumor measuring 3.5cm/3.5cm/3cm, limited to the inferior pole of the right kidney. Right: (background) microscopic hystopatology of the tumor: renal cell carcinoma; (lower image) magnification view
 
 
 
Caption: Sagital section through the right kidney.
Description: A hypoechoic heterogeneous parenchymal mass, appears in the inferior third of the right kidney. The mass produces a deformity of the renal contour.
 
 
 
Caption: Sagital section through the right kidney.
Description: A hyperechoic, shadowing focus (arrow) was seen in front of the spine.
 
 
 
Caption: Transversal section through the right kidney.
Description: Color Doppler examination. A focal dilatation along the right renal artery was seen. This dilatation presents turbulent arterial flow in the lumen.
 
Differential Diagnosis Renal cell carcinoma
Oncocytoma
Angiomyolipoma
Renal abscess
Renal vascular anomaly

 
Final Diagnosis Right renal carcinoma, clear cell variant. Saccular aneurysm of the right renal artery.
 
Discussion Ultrasound revealed a hypoechoic heterogeneous parenchymal mass, measuring 4.5/3cm, located in the inferior third of the right kidney, with deformity of the renal contour (image 1). No abnormal lymph nodes were seen in the renal hilum. The renal vein and the inferior vena cava were patent on Doppler ultrasound. On color Doppler numerous vessels appeared along the periphery of the mass.

A hyperechoic, shadowing focus was seen in front of the spine, at the level of the renal hilum (image 2). On color Doppler a focal dilatation along the right renal artery was suggested (image 3). The left kidney was normal.

The US findings in renal cell carcinoma vary with the size of the lesion. Smaller lesions tend to be homogenous and hyperechoic. As the tumor enlarges it may become isoechoic and be detectable only through its mass effect causing distortion of the renal contour. Larger lesions tend to become heterogeneous and develop hypoechoic elements. Hemorrhage and necrosis within the lesion may give rise to cystic elements.

The peculiarity of our case consisted in the finding of a renal artery aneurysm (RAA) in association with renal cell carcinoma. The RAA was discovered incidentally in this patient and there is no known relationship between RCC and RAA.

Renal artery aneurysm (RAA) is a rare pathological entity. The incidence of renal artery aneurysms in the general population is unknown. Aneurysmal dilation of a renal artery is present when the diameter of that segment exceeds twice that of a normal-appearing artery. RAAs can be classified as extraparenchymal (saccular, fusiform, false/disecting) or intraparenchymal. [1,2]

True aneurysms of the renal artery are very uncommon, and while no single etiology can be forwarded to explain all aneurysms, most authors believe that a defect, perhaps congenital, exists in the vessel wall. When stressed by inflammation-from atherosclerosis, hypertension, or a vasculitis (e.g., polyarteritis nodosa), this results in progressive enlargement of the vessel. The association with atherosclerosis has been doubted by some with some authors believing that the rim calcifications seen with aneurysms, particularly in their later enlarged stages, may be a secondary event, rather than the primary causative factor. [3]

Most RAAs are asymptomatic, but some of the following clinical signs may appear: hypertension, flank pain, hematuria, obstruction of the collecting system, renal infarction or rupture. Our patient’s RAA was asymptomatic. [1, 2]

On ultrasound, a RAA appears as a rounded or oval anechoic zone, located in the renal sinus, anterior to the pelvis. Calcifications of various dimensions may be seen in the wall. At times, cardiac pulsation and hypoechoic parenchymatous areas in the lumen (partial thrombosis) may be observed. In some cases the communication with the renal artery or aorta is obvious. The diagnosis of certainty is determined by Doppler ultrasound, which shows turbulent arterial flow in the lumen. [4] In our case, the presence of RAA was suggested by the US findings but a CT scan was needed for confirmation.

Typical CT findings of RAA include a well-defined mass with wall calcifications and increased density after contrast enhancement, in the arterial phase.

 
Case References 1. Tehrani H., Sawaqued R., Morasch M.: Renal Artery aneurysm, eMedicine World Medical Library, Septembrie 2002.
2. Bulbul M.A., Farrow G.A.: Renal Artery aneurysms, Urology Aug 1992.
3. The Encyclopaedia of Medical Imaging Volume VII.
4. Badea R. I., Dudea S. M.,. Mircea P. A, Stamatian F.: Tratat de Ultrasonografie clinicã. Editura Medicalã Bucureºti. Vol. I. 2000, p. 479.
5. Seki T., Koyanagi T., Togashi M. Et al: Experience with revascularizing renal artery aneurysms: is it feasible, safe and worth attempting? J Urol Aug 1997, 158(2): 357-62.
 
Follow Up The spiral CT scan revealed  a mass measuring 5.2/5.2cm, located on the external surface of the right kidney, in the inferior third. The mass exhibited peripheral enhancement and a hypodense center. The mass presented extracapsular extension at the level of the inferior pole. Right renal and cava veins were patent. There were no focal liver lesions. The tumor was staged as T3N0M0V0. Also noted was a rounded mass on the right renal artery course, measuring 2.1/1.4cm, with wall calcifications and arterial phase increased density. It was interpreted as right renal arterial saccular aneurysm.

A right perifascial nephrectomy was performed, with right renal vein and artery block fixation and right adrenalectomy. The right renal arterial aneurysm was confirmed.

At pathology, the diagnosis was renal cell carcinoma, clear cell variant.

Postoperative evolution was favorable.

 
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