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| LETTER TO THE EDITOR |
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| Year : 2018 | Volume
: 29
| Issue : 2 | Page : 111-113 |
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Renal vein aneurysm
Shih-Huan Su1, Wenghou A O2, Li-Jen Wang3, Hsin-Chia Angela Lin4, Cheng-Keng Chuang1
1 Division of Urology, Department of Surgery, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
2 Department of Urology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
3 Department of Radiology, Chang Gung Memorial Hospital, Taipei, Taiwan
4 Department Of Medical Education, Chang Gung Memorial Hospital, Taipei, Taiwan
| Date of Web Publication | 30-Apr-2018 |
Correspondence Address:
Cheng-Keng Chuang
Chang Gung Memorial Hospital, Taoyuan
Taiwan
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/UROS.UROS_1_18
Renal vein aneurysm (RVA) is a rare disease. Only a few cases have been reported in the past. With Institutional Research Board approval (IRB 201600376B0D001), we reported the case of a 51-year-old female without symptoms and incidental finding of a right renal lesion by renal echo during health examination. Computed tomography (CT) angiography showed a large aneurysm connecting to the right renal vein. Thus, a right RVA was diagnosed. Embolization was not performed due to extremely high probability of untargeted embolization, and the patient preferred outpatient follow-up. CT angiography follow-up was done 6 months later and revealed no obvious enlargement of the aneurysm but an arteriovenous fistula was suspected. The main objective of this report is to differentiate between renal vascular disease and malignant renal neoplasms by reviewing and discussing the available literature. Keywords: Renal vein aneurysm, venous aneurysm, visceral aneurysm
How to cite this article:
Su SH, WenghouA, Wang LJ, Lin HCA, Chuang CK. Renal vein aneurysm. Urol Sci 2018;29:111-3 |
| Introduction | |  |
Renal vein aneurysms (RVAs) are not as common as renal artery aneurysms. The venous aneurysm is defined as a focal dilatation in the absence of associated varicose veins.[1] RVAs include common symptoms such as abdomen pain and hematuria or may even be asymptomatic.[2] They are mostly detected by sonography, computed tomography (CT) with contrast, and magnetic resonance, or even during operations.[3] The treatments of RVAs include aneurysm resection with reconstruction of the renal vein, nephrectomy, and endovascular treatment such as embolization.[4]
| Case Report | | |
We report the case of a 51-year-old Taiwanese female with a history of hepatitis C virus infection who had undergone cesarean section 20 years ago. She denied any systemic disease or medical history otherwise. She came to our clinic due to an incidental finding of a right renal mass by kidney echo in health examination. She denied having any abdominal pain, hematuria, dysuria, fever, flank pain, nausea, body weight loss, vomiting, or stool passage problems. The laboratory tests were unremarkable.
Kidney echo was arranged at the clinic which revealed an anechoic cavity in the hilum of the right kidney [Figure 1]a. Color Doppler showed a mass (2.5 cm) filled with turbulent blood flow and a mosaic pattern in the upper pole of the right kidney [Figure 1]b. There was no obvious hydronephrosis, renal stone, or cyst. Abdominal CT without contrast revealed an oval-shaped, isodense lesion over the right renal hilum [Figure 2]a. The CT of urology with contrast showed a large aneurysm connecting to the right renal vein [Figure 2]b, which enhanced during the venous phase [Figure 2]c. There was no definite inferior vena cava (IVC) and renal vein thrombosis. However, the underlying arterial venous malformations (AVMs) could not be ruled out. Angiography of the right renal artery was subsequently arranged during admission. After superselection into the anterior and posterior divisions of the right main renal artery, a large aneurysm connecting to the right renal vein was noted and is well opacified in the delayed phase of each situation. A right RVA, which was not secondary to the AVM, was highly suspected. Thus, embolization was not performed due to the extremely high probability of untargeted embolization [Figure 3]a and [Figure 3]b. Biopsy was also not arranged due to the high possibility of bleeding. We have well informed the treatment choices to the patient, such as total nephrectomy, autotransplantation, or close observation of the aneurysm size. The patient opted for outpatient department follow-up. | Figure 1: A 2.5-cm anechoic cavity in the hilum over the right upper pole of the right kidney (a). Turbulent blood flow and a mosaic pattern in color Doppler (b)
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 | Figure 2: (a) Abdominal computed tomography without contrast showed a mass over the right hilum. (b) Computed tomography with contrast showed a vascular enhancement in the arterial phase. (c) Aneurysm still enhanced during venous phase
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 | Figure 3: Angiography of the right kidney. (a) There was no obvious enhancement during arterial phase. (b) The aneurysm is well opacified in the delayed phase
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CT of angiography was arranged again 6 months after discharge. It revealed no obvious enlargement of the RVA. However, aneurysmal dilatation of the right renal vein with a hyperkinetic arteriovenous fistula (AVF) or shunting root was noted. An AVF was suspected. She still preferred outpatient follow-up. She was quite well without any symptoms during following up
| Discussion | | |
According to the literature, venous aneurysms are not as common as arterial aneurysms, and usually involve the jugular, popliteal, axillary, intracranial veins, and the superior vena cava.[4] The most common location of venous aneurysms is the portal vein and is usually due to portal hypertension or liver cirrhosis.[4] However, venous aneurysms are quite rare in the renal system. There are only a few cases reported in the past literature and only three reported in 2016.[5],[6],[7]
RVAs are commonly found on the left side rather than the right side. It may be due to the embryological development of the left renal vein, which undergoes more complicated changes because of its increased length,[3],[8] and the hemodynamic factor of the compression of the left renal vein between the superior mesenteric artery and the aorta (nutcracker phenomenon).[5],[9] Most RVAs are caused by the defective development of the media layer or may be secondary to thrombosis, AVF, venous hypertension, or portal hypertension.[3],[10] A giant RVA in a patient with liver cirrhosis was reported in 2016.[5] A case with RVA following renal transplantation was reported, which was mainly caused by vessel injury during organ preparation and implantation.[8] RVAs secondary to AVF are rare. The presentations of these patients include high-output cardiac failure and venous hypertension due to high blood flow.[10],[11] Till now, the definitive etiology of RVAs is still unclear.
RVAs include common symptoms such as abdominal pain and hematuria or may even be asymptomatic.[2] Zhu et al. had reviewed 13 cases of RVAs in adults reported in the English-language literature. The results showed 6 of 13 (46.15%) patients with the symptom of abdominal pain, and 4 (30.77%) with hematuria, and 3 (23.08%) were asymptomatic.[2] However, there can be serious potential complications including rupture, thrombosis, and pressure effects on adjacent structures. Pulmonary embolism is considered to be one of the most severe complications.[7] When these complications arise, the lesion becomes symptomatic and sometimes life threatening. In 2012, Prabakar et al. reported a patient who was diagnosed with thrombosed venous aneurysm of the left renal vein. Retrohepatic IVC thrombosis was also found which caused the dilation of the intrahepatic IVC and common iliac and external iliac veins. It was either an embolism or a progression of the thrombus from the renal vein, which caused the IVC thrombosis. However, thrombosed aneurysms can also occur due to the obstructed outflow. Hence, thrombosis is not only the cause of aneurysm but also the consequence.[12]
The main objective of this report is to make a differentiation between renal vascular disease and renal malignant neoplasms, since the image of a RVA can appear similar to a renal tumor. According to the articles we reviewed, RVAs usually appear to be an anechoic saccular structure between the renal sinus and IVC arising from the renal vein.[7] However, we have to distinguish it from a renal cyst using Doppler. Similar to our case, RVA is characterized by turbulent high-blood flow and has a characteristic mosaic pattern. On CT, RVA appears similar to those aneurysms in other anatomical locations.[13] It usually appears to be a saccular, well-defined, and homogeneous mass in the renal hilum and will still enhance during the venous phase. Unlike RVA, malignant neoplasms such as renal cell carcinoma originate within the renal cortex, and renal transitional cell carcinomas are located over the collecting system. On magnetic resonance (MR) images, a gradation in signal intensity is seen following administration of gadolinium-contrast material (”layered gadolinium sign”).[14] However, there was no MR image in our case. Moreover, it was important to differentiate between RVAs and renal artery aneurysms, as they both require different treatments. As we mentioned above, RVAs still showed enhancement during the venous phase on CT or angiography, while renal artery aneurysms did not. Angiography of the renal artery is still the gold standard to detect the RVA, which will not show any abnormality during the arterial phase.
Due to the rarity of the RVA, the optimal treatment still remains unclear. Available treatments include aneurysm resection with reconstruction of the renal vein, nephrectomy, and endovascular treatment such as embolization.[4] Anticoagulant therapy should be considered in some cases to reduce the risk of pulmonary embolism.[8] However, the treatment of the RVA should be considered individually. Regarding our case, embolization was not performed due to an extremely high probability of untargeted embolization. The main limitation of our study was the accuracy of diagnosis, which should be included in the pathological study of the intraoperative specimen.
In conclusion, RVA is an extremely rare disease. The definite etiology and optimal treatment are still quite unclear. Although it is usually asymptomatic, its complications may be life threatening, and this should be kept in mind during diagnosis.
The informed patient consent was waived by the Institutional Review Board of Chang Gung Medical Foundation. (IRB No.: 201600376B0).
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 2. | Zhu Y, Zhu X, Liu W, Xu Y, Tang L. Incidental finding of right renal vein aneurysm in a patient with hematuria. Urology 2015;85:e9-10. |
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| 11. | Verma R, King A, Sasani A, Gupta V. Endovascular repair of a giant renal vein aneurysm arising from an arteriovenous fistula. J Vasc Surg 2011;54:91S. |
| 12. | Prabakar D, Bit N, Vidyasagaran T, Amalorpavanathan J, Sritharan N, Elancheralathan K, An extremely rare case of an incidentally detected renal vein aneurysm and review of literature. Veins Lymphatics 2012;1:51. |
| 13. | Khader SM, Saleeb SF, Teplick SK. General case of the day. Left renal vein aneurysm. Radiographics 1999;19:1683-5. |
| 14. | Krinsky G, Johnson G, Rofsky N, Shapiro R, Yang B, Weinreb J, et al. Venous aneurysms: MR diagnosis with the “layered gadolinium” sign. J Comput Assist Tomogr 1997;21:623-7. |
[Figure 1], [Figure 2], [Figure 3]
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