Simultaneous resection of bilateral renal aneurysm and renal tumor followed by kidney autotransplantation: a case report

Abstract

With the continuous advancement of diagnostic technologies, an increasing number of renal and renal vascular lesions are being detected. However, cases involving renal tumors concurrent with renal vascular lesions remain exceedingly rare, and there is currently no established consensus regarding their optimal diagnosis and treatment strategies. Renal tumors often necessitate radical nephrectomy, which typically precludes the preservation of the affected kidney. In this report, we present the case of a young female patient diagnosed with a right-sided renal tumor in conjunction with bilateral renal artery aneurysms, who successfully underwent a kidney-preserving surgical procedure. Although preoperative imaging and MDT review suggested a malignant renal neoplasm, final histopathology demonstrated aneurysmal vascular wall with fibrointimal hyperplasia, hyalinization, calcification/ossification, and luminal thrombosis, without evidence of a true renal tumor. This radiologic–pathologic discordance explains the mass-like appearance on imaging.

Introduction

Renal artery aneurysm (RAA) is a relatively rare vascular condition with a complex and poorly understood natural history. The exact incidence of RAA remains uncertain, with reported rates ranging from 0.01% to 0.09% in the literature [1, 2].Historically, due to underdeveloped diagnostic techniques and the often asymptomatic nature of RAA, many cases were misdiagnosed or overlooked. In recent years, the advent of advanced imaging modalities such as computed tomography angiography (CTA) has significantly improved the detection rate of RAA, though the overall number of diagnosed cases remains limited. Bilateral RAA is even more uncommon.

In contrast, renal tumors, irrespective of their benign or malignant nature, represent space-occupying lesions originating from the renal parenchyma and are among the most frequently encountered urological masses. Failure to promptly manage these tumors can lead to serious complications, including hemorrhage from ruptured benign tumors or metastatic spread in the case of malignancies [3], both of which are potentially life-threatening. Synchronous partial nephrectomy with RAA repair has been reported. However, to our knowledge, reports in young women with bilateral RAAs managed in a single stage by ex vivo partial nephrectomy, venous interposition reconstruction, and renal autotransplantation are exceedingly rare.

Case report

The patient is a 25-year-old female who initially presented to a local hospital with complaints of dizziness and was found to have a space-occupying lesion in the right kidney. An abdominal CT scan revealed a high likelihood of a right renal artery aneurysm with concomitant intraluminal thrombosis, a left renal artery aneurysm, and a solid isodense mass within the right renal parenchyma. Subsequently, the patient sought further evaluation and management at our institution. She had been diagnosed with hypertension over two years prior, with a peak blood pressure of 170/110 mmHg. At presentation, the patient was taking amlodipine besylate 5 mg once daily and valsartan 80 mg once daily. Her blood pressure was well-controlled with treatment. The patient had no history of other underlying medical conditions, smoking, alcohol consumption, or exposure to specific chemicals or radiation. There was also no family history of similar diseases.

Upon admission, the patient’s glomerular filtration rate (GFR) was within normal limits, with a serum creatinine (Scr) level of 42.9 µmol/L and a blood urea nitrogen (BUN) level of 3.83 mmol/L. Additionally, the patient presented with mild hypokalemia, with a serum potassium concentration of 3.41 mmol/L. Given the patient’s history of hypertension, further endocrine evaluations were conducted, which indicated that the renal mass was unlikely to be of adrenal origin. Rather, the bilateral renal artery aneurysms were considered as a potential contributor to her hypertensive condition.The contralateral (left) renal artery aneurysm was asymptomatic and judged suitable for observation. We arranged surveillance with interval vascular imaging and clinical review.

Further diagnostic investigations, including color Doppler ultrasound, renal CT, and computed tomography angiography/venography (CTA/CTV), were performed. These revealed a right renal artery aneurysm measuring approximately 53 × 32 mm, with evidence of multiple mural thrombi. In addition, a space-occupying lesion in the right kidney, measuring approximately 41 × 35 mm, was identified, causing compression of the renal pelvis and calyces. The possibility of a tumor could not be excluded. A left renal artery aneurysm was also confirmed. Pre-operative imaging data were obtained and showed in Fig. 1.

Fig. 1.

Pre-operative imaging data. Fig 1A and 1B show the CT and CTA images obtained before the operation

Owing to the patient’s young age, female sex, and bilateral RAAs, we performed targeted screening. Detailed history and physical examination were unremarkable; multibed duplex ultrasonography, transthoracic echocardiography, and routine laboratory, rheumatologic tests were normal. Genetic testing was not undertaken at presentation given the low pre-test probability; surveillance with interval vascular imaging was arranged.

Given the patient’s young age and the anticipated high demand for renal function in the future, as well as the patient’s strong preference for kidney preservation, a multidisciplinary team (MDT) meeting was convened. The team included specialists from vascular surgery, the transplant center, interventional radiology, anesthesiology, and surgical nursing. Considering the complexity of the patient’s condition, which involved a large renal artery aneurysm and the proximity of the renal mass to the renal hilum, combined with experiences drawn from both domestic and international cases, a comprehensive surgical plan was developed. The proposed treatment included a 3D laparoscopic right nephrectomy, ex vivo partial nephrectomy of the right kidney, resection of the right renal artery aneurysm, substitution of the artery with the great saphenous vein, and autologous right kidney transplantation.

The surgery began with a laparoscopic right nephrectomy, performed via a 12-mm peri-umbilical camera port and three 10-mm working ports. The colon was mobilized along the paracolic gutter to expose the right kidney; a 5-cm hilar bulge compressed the renal vein. Within Gerota’s fascia, the ureter and renal vessels were isolated and ligated with Hem-o-lok clips, and the kidney was extracted through a right lower-quadrant mini-incision. On the back table, the graft was iced and cold-perfused with a citrate-based solution. The hilar mass was excised (ex vivo partial nephrectomy), and parenchymal renorrhaphy was performed with a continuous knotless suture using a sliding-clip technique (Hem-o-lok as stoppers). The aneurysmal arterial branch was resected; a great saphenous vein conduit (≈ 10 cm) was anastomosed end-to-end to the branch, and the second renal arterial branch was anastomosed end-to-side to the conduit, completing branch-preserving reconstruction.

The entire procedure lasted 6 h, with a cold ischemia time of 56 min. Intraoperative blood loss was approximately 500 mL, necessitating the transfusion of 2 units of packed red blood cells and 150 mL of fresh frozen plasma. Anesthesia was uneventful, and the patient’s vital signs remained stable throughout the operation. The entire postoperative specimen was submitted for comprehensive histopathological examination. Examination of the resected specimen (right renal ‘mass’ and right RAA) revealed aneurysmal vascular wall showing fibrous tissue hyperplasia, hyaline degeneration, calcification with ossification, and intraluminal thrombosis. Immunohistochemistry: HMB45 (−), Melan-A (−), SMA (+), Desmin (focally +), CK-pan (−), S-100 (−), Ki-67 ~ 1%, CD34 (−). No renal epithelial or melanocytic neoplasm was identified. The surgical procedure and pathology findings are shown in Fig. 2.

Fig. 2.

Features during the operation. Fig 2A shows the Aneurysm fused with the renal vein(red arrows), Fig 2B shows the process of gaining the great saphenous vein. Fig 2C provides a comprehensive view and cross-sectional view of the ex vivo tumor, while Fig 2D shows a microscopic view of the pathology specimen

No postoperative complications were observed. Postoperative monitoring of renal function revealed no significant impairment, and the patient was discharged on postoperative day 11 with stable kidney function. The relevant laboratory parameters showed no significant abnormalities before or after surgery (Table 1). A schematic timeline is provided in Fig. 3.

Table 1.

Preoperative and postoperative test indicators. The concentrations of BUN, Scr, serum potassium, serum sodium and eGFR in patients were within the normal range both preoperatively (3 days before surgery) and postoperatively (1 day, 10 days, and 30 days after surgery)

Time	Before Surgery	After surgery
	3 Days	1 Day	10 Days	30 Days
Blood Urea Nitrogen (mmol/L)	3.83	1.67	2.51	4.86
Serum Creatinine (µmol/L)	42.90	61.00	52.80	65.00
Serum Potassium Ion (mmol/L)	3.41	4.32	4.19	4.25
Serum Sodium Ion (mmol/L)	139.00	136.20	137.80	137.00
eGFR* (mL/min/1.73 m²)	134.0	123.0	127.8	116

^*eGFR calculated by the CKD-EPI 2021 race-free equation

Fig. 3.

Schematic timeline illustrating key clinical events. The “–” sign before a day number indicates time points before the day of surgery (Day 0)

At 30 days, renal function remained within normal limits, blood-pressure control was stable without medication escalation, and serum potassium normalized; beyond 30 days the clinical course remained stable. Owing to patient-related constraints, vascular imaging has not yet been obtained; surveillance duplex ultrasonography is scheduled at the next visit and at 6 and 12 months thereafter, with CTA/MRA if duplex is nondiagnostic or if clinical status changes. Long-term monitoring will include periodic serum creatinine/eGFR and albuminuria assessments and home blood-pressure logs; the contralateral renal artery aneurysm follows the same schedule.

Discussion

Extensive research has been conducted on the diagnosis and treatment of renal tumors and renal artery aneurysms, particularly for renal tumors, for which well-established diagnostic and therapeutic guidelines are available [3]. However, cases involving the coexistence of renal tumors and renal artery aneurysms remain relatively rare in clinical practice, especially in patients with bilateral renal artery aneurysms and concurrent renal tumors. Representative reports document coexistent renal tumor and RAA across different scenarios, including renal cell carcinoma(RCC) with ipsilateral RAA treated by radical nephrectomy [4], synchronous in-situ partial nephrectomy with RAA repair [5], and contralateral RAA managed with aneurysmectomy in the same session as nephrectomy [6]; benign coexistence has also been described, such as renal hemangioma with RAA [7], framing both the rarity and management spectrum relevant to our case. According to the natural history of the disease, these patients are typically elderly [8]. The present case, involving a 25-year-old female, is exceptionally uncommon. To our knowledge, reports in young women with bilateral RAAs managed in a single stage by ex vivo partial nephrectomy, venous interposition reconstruction, and renal autotransplantation are exceedingly rare. Importantly, despite preoperative concern for malignancy, final histopathology demonstrated aneurysmal vascular wall with fibrointimal hyperplasia, hyalinization, calcification, ossification, and luminal thrombosis, without evidence of a renal neoplasm.

When preoperative CTA/CTV findings are considered together with the final histology, the apparent “mass” near the hilum is best explained by the aneurysmal sac and organized thrombus rather than a separate renal neoplasm. In this setting, we favored definitive excision and vascular reconstruction; the ex vivo strategy under cold ischemia provided superior exposure for precise thrombectomy and multi-branch repair while preserving nephrons and addressing the oncologic uncertainty and complex hilar anatomy.

We also considered endovascular alternatives but did not choose them after multidisciplinary review. The aneurysm was large, hilar and branching with mural thrombi, yielding short landing zones and a substantial risk of branch jailing or parenchymal loss; moreover, covered stenting would require dual antiplatelet therapy during simultaneous tumor surgery. By performing ex vivo, branch-preserving reconstruction concurrently with back-table tumor excision, we achieved single-stage repair with controlled ischemia and maximal nephron preservation.

Our cold ischemia time (56 min) aligns with published ranges for bench ex vivo nephron-sparing surgery with renal autotransplantation: series report CITs from ~ 35–42 min in small ex vivo PN cohorts to ~ 90–150 min and ~ 121 ± 26 min in larger or complex reconstructions, with longer times in highly complex repairs [9–11].

From a nephrology perspective, the presentation with hypertension and mild hypokalemia and the postoperative normalization of potassium and improved blood-pressure control support restoration of renal perfusion; reporting the preoperative regimen (amlodipine plus valsartan) is important context for interpreting potassium and blood-pressure changes. We acknowledge that paired renin or aldosterone assays were not obtained perioperatively; outpatient RAAS testing has been arranged and is noted as a limitation.

Management of disease beyond the operated side also requires clarity. Given the left-sided lesion’s asymptomatic presentation and stable imaging features, we adopted conservative surveillance with structured clinical review and scheduled vascular imaging, together with blood-pressure and kidney-function monitoring; intervention will be reconsidered if interval growth, morphologic change, or new symptoms occur. Because the patient is a young woman, we advise preconception vascular imaging to confirm graft patency and renal perfusion (CTA, or non-contrast MRA when radiation avoidance is preferred), optimize blood pressure, eGFR, and albuminuria, and plan multidisciplinary care with nephrology and maternal–fetal medicine during pregnancy; ultrasound and MRI are the imaging modalities of choice in pregnancy, and vigilance for hypertension/preeclampsia is warranted given the elevated risk reported in transplant cohorts, while acknowledging that evidence specific to renal autotransplantation in pregnancy is limited [12].

RAAs are often asymptomatic, with many cases being incidentally diagnosed during routine imaging studies, such as ultrasound. In this case, the patient presented with hypertension and a right renal artery aneurysm measuring over 2 cm in diameter. Given the patient’s young age and reproductive potential, surgical intervention for the renal artery aneurysm was warranted. In addition, the right renal parenchymal mass posed a significant risk if left untreated. Therefore, simultaneous management of both conditions was necessary.

Given this uncertainty at presentation, an ex vivo approach allowed simultaneous oncologic management of a suspicious lesion and precise aneurysmal repair under controlled ischemia. The selection of the surgical approach in this case was guided by several key considerations. First, the patient presented with bilateral renal artery aneurysms, including a large aneurysm on one side, combined with a renal lesion that could not be definitively diagnosed preoperatively through non-invasive methods. Confirmation of the renal lesion required surgical resection. However, performing a partial nephrectomy is challenging in this scenario due to the need for renal artery occlusion, which is complicated by the presence of a large renal artery aneurysm. Therefore, an initial right nephrectomy followed by ex vivo tumor resection was deemed the optimal approach.

Secondly, this surgical technique has been well established in the management of isolated renal artery aneurysms. Bench surgery, specifically ex vivo renal procedures, has proven to be a successful strategy in treating renal artery aneurysms. A review of 55 cases from 1975 to 2020 highlighted that, when interventional therapies are unsuitable, autotransplantation has emerged as one of the preferred options for preserving kidney function in patients with renal artery aneurysms [5]. In this case, a laparoscopic radical nephrectomy was performed to minimize intraoperative bleeding, reduce postoperative complications, and expedite the patient’s recovery. Additionally, given the patient’s strong desire to preserve her kidney, a minimally invasive approach was prioritized.

Nephron preservation in this case was determined by the reconstructive strategy—bench (ex vivo) partial nephrectomy with autotransplantation—rather than by the operative approach. The nephrectomy phase may be performed either open or minimally invasive; we elected laparoscopy to reduce blood loss, facilitate recovery, and leverage magnified hilar visualization, while maintaining a low threshold for conversion if exposure or safety were suboptimal. The ex vivo phase then provided cold-ischemic conditions for precise tumor excision, meticulous thrombectomy, and branch-preserving arterial reconstruction. In centers with different anatomy or expertise an open approach would be equally reasonable; thus, approach selection was individualized, but the kidney-sparing outcome derived from the bench reconstruction plan.

For patients with a history of renal masses combined with renal artery aneurysms, previously reported surgical options have included either laparoscopic partial nephrectomy or radical nephrectomy. These approaches were primarily chosen based on the tumor’s anatomical accessibility or the advanced age of the patient [13, 14].Therefore, the surgical approach selected in this case was tailored to the patient’s unique clinical presentation.

Given the rarity of this condition, there are no established guidelines or consensus for the management of renal tumors combined with renal artery aneurysms. It is essential to adopt a personalized approach that considers the patient’s overall health, lesion location, potential surgical impact, and the patient’s preferences for treatment.

Authors’ contributions

Xuhao Liu: Data curation; Resources; Writing–original draft, review & editing.Pinghong Dao: Investigation.Yuanqing Dai: Investigation.Miao Mo: Investigation.Minfeng Chen: Conceptualization; Project administration.

Funding

This research was supported by the National Natural Science Foundation of China (Grant Nos. 82170789 and 81974100).

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

We comprehensively introduced the purpose and relevant contents of this study to the patient, ensuring full protection of the patien’s privacy. The patient participated in this study voluntarily.

Consent for publication

All the co-authors of this article have consented to its publication.

The patient gave her written informed consent for the publication of all data and images.

Competing interests

The authors declare no competing interests.