Bilateral thoracic renal arteries in a 29-year-old undergoing evaluation of a right retroperitoneal mass

Abstract

Thoracic renal arteries (TRAs), defined as renal arteries originating above the diaphragmatic hiatus from the descending thoracic aorta, represent an exceptionally rare anomaly reported in less than 0.1% of the general population. Traditionally, they are predominantly described as unilateral right-sided variants with origins at the T10-T12 vertebral levels. We report the case of a 29-year-old female with an indeterminate right retroperitoneal mass requiring image-guided biopsy. Upon review of cross-sectional imaging for preprocedural planning, contrast-enhanced CT incidentally revealed bilateral TRAs. On the right, there was a single, dominant thoracic renal artery arising from the aorta at the bottom of T12 vertebral body. The left kidney had a dominant left renal artery in the typical location at the top of L2, with a smaller accessory thoracic renal artery arising from the aorta at the midportion of T11. Embryologically, the presence of TRAs reflects the persistence of cranial mesonephric arterial segments that normally regress as the kidneys ascend. While unilateral TRAs have been sporadically documented, bilateral thoracic origins remain extraordinarily uncommon. Such high-level renal artery origins pose a heightened risk for iatrogenic injury during retroperitoneal procedures and may have implications for thoracic endovascular aortic repair (TEVAR), open thoracoabdominal surgeries, and transplant planning. Recognizing the potential for bilateral TRAs is crucial for interventional radiologists and vascular surgeons. Meticulous imaging review, including arterial-phase reconstructions, serves to avoid complications such as hemorrhage, inadvertent arterial occlusion, or renal ischemia. This case underscores the importance of considering aberrant vascular anatomy in patients undergoing interventions.

Introduction

Renal artery variations occur in a substantial proportion of the population, estimated between 25% and 40%¹. These variations commonly manifest as accessory or multiple renal arteries branching from the abdominal aorta at or below the L1–L2 vertebral levels. While subdiaphragmatic accessory renal arteries are more common and often asymptomatic, thoracic renal arteries (TRAs)—those arising above the diaphragmatic hiatus—are exceedingly rare, with an incidence below 0.1% [1,2]. These thoracic variants can have significant clinical implications if undetected, particularly during interventional and surgical procedures.

The renal arteries typically originate from the abdominal aorta between the first and second lumbar vertebrae. The most common configuration originates from the lower margin of the L1 vertebra (25%) on the right side and from the upper margin of the L2 vertebra (24%) on the left side³. Anatomically, TRAs represent a striking deviation from this norm, emerging from the thoracic aorta typically at the level of the 10th to 12th thoracic vertebrae and coursing through the diaphragmatic crura to reach the renal hilum.

Typically, TRAs are documented as solitary right-sided vessels discovered incidentally through imaging [2,4]. In a comprehensive review of the literature, Ishida et al.⁵ noted that all previously reported thoracic renal arteries were found on the right side. This anatomical bias may be related to the right renal arterial orifice typically being superior to that on the left side [3].

The clinical significance of TRAs has gained recognition with multiple case reports highlighting their potential implications in various interventional procedures, including renal transplantation, vascular stent placement, renovascular hypertension assessment, and reconstructive aortic surgery [3,5,6].

Despite increased awareness, isolated bilateral TRAs remain largely undocumented in medical literature. While Święch et al. described supradiaphragmatic origins of multiple abdominal vessels in a single case (including the celiac trunk and superior mesenteric artery along with renal arteries), our presentation of bilateral TRAs without concurrent anomalies of other major abdominal vessels represents a distinct embryological variant [5]. This case therefore contributes a novel observation to the limited literature on high-origin renal arteries and expands our understanding of the spectrum of these rare vascular anomalies.

This case report details a 29-year-old female incidentally found to have bilateral TRAs when reviewing cross-sectional imaging to plan for CT-guided biopsy of an indeterminate right retroperitoneal mass. We highlight embryologic considerations, clinical significance, and interventional implications for these rare vascular anomalies.

Case presentation

A 29-year-old female (gravida 1 para 1) with a medical history of obesity (BMI ∼45) and mild chronic anemia presented in mid-2024 with intermittent right lower quadrant pain. Laboratory studies revealed normal renal function (creatinine 0.8 mg/dL, estimated glomerular filtration rate >90 mL/min/1.73m²) and unremarkable coagulation parameters (INR 1.17, platelets 477). She had no recorded history of hypertension or previous abdominal surgeries.

Abdominal CT initially excluded appendicitis but uncovered moderate cholelithiasis with no acute findings of cholecystitis. Incidentally, a 5 cm right retroperitoneal lesion was found. For further delineation, the patient underwent an MRI of the abdomen in January 2025, showing a T1-isointense, T2-hypointense mass measuring approximately 5.0 × 3.0 cm, located separate from her right adrenal gland and kidney. Differential diagnoses included atypical angiomyolipoma, lymphoma, sarcoma, retroperitoneal fibrosis, and extramedullary hematopoiesis. Owing to its indeterminate imaging characteristics, she was subsequently referred for a CT-guided biopsy.

CT and multiplanar reformatting revealed bilateral thoracic renal arteries.

• •The right TRA originated from the lower thoracic aorta at the bottom of T12 vertebral level and coursed obliquely through the right diaphragmatic crus to enter the renal hilum (Fig. 1).
• •The left accessory TRA also originated from the thoracic aorta at the midportion of T11 vertebral body, extending to the upper pole of the left kidney. Of note, the left gonadal vein was duplicated; a normal anatomic variant (Figs. 2 and 3).

Fig. 1.

Contrast-enhanced T1 fat-saturated axial image demonstrates a 5.0×3.0 cm retroperitoneal mass, isolated from the right kidney and adrenal gland (arrow). A right thoracic renal artery is seen coursing through the right diaphragmatic crura (arrowhead).

Fig. 2.

Coronal 3D MIP reformatted image utilizing thin slice acquisitions demonstrates bilateral thoracic renal arteries originating from the thoracic aorta (arrows).

Fig. 3.

Coronal 3D MIP reformatted image utilizing thick slice acquisitions again demonstrates the course of a right thoracic renal artery (arrow), in addition to a duplicated left gonadal vein (arrowhead).

The patient underwent a CT-guided biopsy under moderate sedation. After successful needle placement using intermittent CT guidance to avoid traversing the right TRA, multiple core samples were obtained. Postprocedural imaging showed no evidence of hemorrhage. The patient was monitored in the recovery suite for 4 hours, tolerated the procedure well, and was subsequently discharged. Cytopathology was diagnostic for ganglioneuroma.

Ganglioneuromas are fully differentiated, benign tumors of sympathetic neural–crest origin and possess an exceedingly low malignant potential. After histologic confirmation, the case was reviewed by surgery and radiology teams. Because the patient was entirely asymptomatic with regards to the mass, and complete excision would have required an extensive retroperitoneal dissection with attendant morbidity, consensus favored active surveillance rather than immediate surgery. The patient was scheduled for a contrast enhanced MRI of the abdomen in 6 months from the date of biopsy to monitor the mass.

Discussion

Renal arteries typically originate from the lateral aspect of the abdominal aorta at the L1–L2 vertebral levels. Common variations include accessory vessels arising below the diaphragm, which have been reported in up to one-third of the population¹. In contrast, supradiaphragmatic origins (TRAs) are exceedingly rare, with an incidence under 0.1% [2]. This rarity likely contributes to the limited awareness among interventionalists until the past 2 decades, during which advanced imaging techniques have facilitated the detection of TRAs in otherwise asymptomatic individuals [3,4].

From an embryological perspective, TRAs are presumed to arise from cranial mesonephric arteries that fail to regress during fetal kidney ascent [6,7]. Felix proposed 9 pairs of lateral mesonephric arteries that arise from the dorsal aorta in an 18-mm embryo (at approximately the 8th week), divided into 3 groups: cranial, middle, and caudal [9]. The cranial group comprises the first and second mesonephric arteries, which are located proximal to the celiac trunk of the abdominal aorta. The persistence of these primitive cranial mesonephric vessels is thought to be responsible for the high anomalous renal arterial supply in TRAs [6].

The embryological basis for our patient's bilateral TRAs reflects a significant developmental anomaly. During kidney ascension from the pelvis to the upper retroperitoneum, lateral mesonephric arteries normally regress as new, more caudal arteries form [5,6]. In our case, cranial mesonephric branches persisted bilaterally—an unusual phenomenon that diverges from the predominantly right-sided pattern documented in the literature [2,4,5]. This bilaterality suggests a more extensive embryological variation than typically encountered, where the persistence of cranial vessels usually affects only 1 side.

While most reported TRAs originate at the level of T11 [5], our patient's right TRA emerged at the bottom of T12. In addition, the presence of an accessory left TRA represents an exceptional finding, as left-sided thoracic origins are exceedingly uncommon. Stinson et al. [8] documented 1 such case of left TRA, but our patient's bilateral presentation appears to be extraordinarily rare.

The interventional significance of TRAs extends to several clinical scenarios:

Retroperitoneal biopsy and resections:

Sudden blood vessel traversal or inadvertent needle puncture of a TRA can lead to significant hemorrhage, pseudoaneurysm, or renal parenchymal infarction. Preprocedural imaging, as demonstrated in our case, allows for trajectory planning to avoid these anomalous vessels, highlighting the importance of vascular mapping [3]. Early identification of high-level renal vessels on cross-sectional imaging guides needle trajectory optimization and helps the radiologist prepare for potential emergent vascular interventions [2,6]. Specifically, in the context of CT-guided biopsies, such as the 1 performed on our patient, real-time knowledge of TRA location enables precise needle placement, minimizing the risk of vascular complications and ensuring a diagnostic sample is safely obtained. This approach prevents the possible pitfall of focusing solely on the target kidney's vasculature while overlooking anomalous vessels supplying the contralateral kidney, which could be inadvertently injured during procedural planning or access. In our patient, recognition of bilateral TRAs allowed for a safer approach to the biopsy of the right retroperitoneal mass, avoiding the unusual high-level feeding vessel.

Vascular embolization procedures

In scenarios such as trauma or tumor-related hemorrhage, angiography with embolization may be considered. TRAs complicate catheterization by requiring navigation proximal to the diaphragm, potentially raising the risk for complications [10]. Sueyoshi et al. [10] reported a case emphasizing the challenges in catheter navigation in the presence of a high-origin renal artery, underscoring the need for careful consideration of vascular anatomy in embolization planning. When considering renal artery embolization for indications such as hemorrhage control or management of arteriovenous malformations, the presence of a TRA necessitates careful consideration of catheter selection and navigation strategies. Failure to appreciate a high origin can result in unsuccessful catheterization, prolonged procedure time, and increased radiation exposure to both patient and operator. Moreover, when multiple renal arteries are present, including a TRA and a normally positioned artery from the abdominal aorta, a complete embolization may be difficult or impossible to achieve if only 1 vessel is targeted.

Thoracic Endovascular Aortic Repair (TEVAR) and Thoracoabdominal Surgery Significant risk arises if a stent graft deployed in the descending thoracic aorta occludes a high-origin renal artery, producing partial or complete renal infarction [8,11]. Stinson et al. [8] presented a case where a left TRA was incidentally discovered, emphasizing the potential for inadvertent coverage during TEVAR. Delasotta et al. [6] also underscore the critical preoperative awareness for vascular surgeons to consider fenestrated grafts or alternative strategies in such cases to prevent renal malperfusion. Preoperative awareness of a thoracic-level origin helps vascular surgeons consider fenestrated graft designs or alternate coverage strategies while also anticipating the possibility of renal malperfusion if inadvertent coverage occurs. During TEVAR, inadvertent coverage of a TRA can result in devastating consequences, including acute renal failure, renovascular hypertension, and the need for emergent renal revascularization. Precise knowledge of the renal artery origin is paramount for proper stent graft planning and deployment. Similarly, in open thoracoabdominal aortic repair, recognizing TRAs allows surgeons to modify their surgical approach, avoiding inadvertent transection or injury to these anomalous vessels. Failure to do so can lead to significant intraoperative hemorrhage and compromise renal perfusion.

Transplantation and Donor Evaluations Comprehensive donor imaging for renal transplantation must characterize any aberrant vessels, given that multiple arteries or high takeoffs can extend operative time, elevate complication rates (e.g., ureteral ischemia), and necessitate special anastomoses [3]. Bilateral TRAs would complicate both laparoscopic donor nephrectomy and subsequent graft revascularization if a thoracic-level donor artery must be implanted or matched to the recipient’s vessels. Some case series [2,4] have tentatively linked TRAs with hypertension or diaphragmatic compression syndromes causing partial luminal stenosis [2,4]. However, many patients remain normotensive and asymptomatic, implying that if the orifice and arterial caliber are sufficient to maintain normal perfusion, then no overt pathology may emerge. In our patient, no hypertension was documented, but long-term monitoring was recommended.

Renal Artery Denervation Renal sympathetic denervation (RDN) has emerged as an innovative catheter‐based therapy for resistant hypertension, directly addressing the autonomic regulation of blood pressure. Variations—such as accessory renal arteries, early branching patterns, and high-origin renal arteries as seen in our patient—may harbor significant periarterial nerve networks that lie beyond the conventional ablation zone of the main renal artery. The presence of accessory renal arteries can significantly affect the efficacy of RDN procedures, with patients having incompletely denervated accessory renal arteries showing significantly less blood pressure reduction than those with bilateral single renal arteries [12]. The anatomical distribution of these nerves is critical, as nerve density varies according to both longitudinal and circumferential locations around the renal artery, with fewer nerves in distal segments and dorsal regions [13]. Sakura et al.[14] histological studies revealed that approximately 75% of nerves are located within 4.28 mm of the arterial lumen. Procedural technique significantly impacts outcomes, with more complete ablation patterns and higher numbers of ablation attempts correlating with greater blood pressure reductions. Failure to identify and effectively treat these variant vessels may result in incomplete nerve disruption, thereby diminishing the antihypertensive efficacy of the procedure. Although robust data from large-scale trials is lacking, current evidence supports a comprehensive imaging evaluation of all renal arterial branches to ensure thorough renal sympathetic denervation.

Conclusion

This report describes a 29-year-old female with bilateral thoracic-level renal arteries discovered incidentally during the evaluation of a right retroperitoneal mass. Bilateral TRAs represent an unusual vascular phenomenon, emphasizing the importance of meticulous preprocedural vascular mapping, particularly when performing biopsies or interventions near the diaphragmatic crura. The embryologic basis—persistence of cranial mesonephric branches—underscores the variability of renal artery origins.

As imaging modalities such as dynamic CT angiography and 3D reconstructions become routine, more TRAs—both unilateral and bilateral—may be discovered, potentially revealing a broader variation in embryologic vascular persistence than previously recognized [3,5]. Large-scale databases or multicenter retrospective studies might clarify the true incidence of bilateral TRAs and characterize potential associations with renal function or vascular complications.

Given the potential for major hemorrhage or renal ischemia if such arteries are compromised, thorough cross-sectional imaging and multidisciplinary collaboration significantly enhance both procedural safety and patient outcomes. As imaging techniques advance, it is likely that additional cases of bilateral TRAs will appear in the literature, refining our understanding of their embryogenesis, clinical significance, and long-term implications.

Patient consent

We confirm that written, informed consent for publication of the case details was obtained from the patient involved in this case report. The consent encompasses the patient's agreement to the disclosure of their health information and the publication of their anonymized data and images in relation to this study.