Robot-assisted Partial Nephrectomy With Selective Artery Clamping for Renal Cell Carcinoma in Horseshoe Kidney

Abstract

Background

Robot-assisted partial nephrectomy (RAPN) has become the standard treatment for small renal tumors, including highly complex cases. However, applying RAPN to renal tumors in the horseshoe kidney (HSK) is clinically challenging due to malformations and complex blood supply. Herein, we present two cases of RAPN in patients with HSK treated using selective artery clamping methods.

Case Reports

A 61-year-old male with a 15 mm renal tumor located on the upper pole of the right HSK was referred to our Department. The patient underwent RAPN via the transperitoneal approach, following a three-dimensional computed tomography (3D-CT) assessment. Additionally, before surgery, we confirmed which renal arteries would be clamped in surgery by examining the kidney regions supplied by each renal artery. The second patient referred to our Department, a 45-year-old male, had a 46 mm renal tumor located on the isthmus of the HSK. His tumor received blood supply from two renal arteries, with the bilateral collecting systems converging and forming a ureter on 3D-CT. The patient underwent RAPN through an intraperitoneal approach in the semi-lateral position, with port placement lower than in standard RAPN. Pathological examinations revealed clear-cell renal cell carcinoma with negative surgical margins in both cases. Both patients had no recurrences or metastases at 53 and 13 months post-surgery, respectively.

Conclusion

We present cases successfully treated with RAPN with selective artery clamping methods for HSK using 3D-CT without encountering complications, even in isthmus tumors.

Robot-assisted partial nephrectomy (RAPN) for T1 renal tumor has become established as a minimally invasive nephron-sparing surgery with excellent perioperative and oncological outcomes (1,2). Consequently, it is increasingly performed in more complex cases, including renal hilar and highly complex renal tumors (3,4).

Horseshoe kidney (HSK) is one of the most common congenital urological anomalies, affecting approximately 0.15% to 0.25% of the human population (5) and up to 6% of patients diagnosed with renal cell carcinoma (RCC) (6). Typically, renal tumors in HSK are managed through open surgery due to the presence of malformations, a complex blood supply, and abnormalities in the blood supply system (7). However, there are limited reports on the use of RAPN for treating renal tumors in patients with HSK. Herein, we present two cases of RCC in HSK, one of which was located in the isthmus and successfully treated with RAPN using selective artery clamping methods.

Case Reports

Case 1. A 61-year-old Japanese male with HSK presented at our Department with a renal tumor incidentally found on computed tomography (CT). He had no relevant medical or family history, and his laboratory data and urine test results were within normal ranges. However, three-dimensional CT (3D-CT) revealed a 15 mm diameter tumor at the anterior and upper pole of the right HSK, supplied by two renal arteries with early branches from the abdominal aorta (Figure 1A and B). To plan the surgery, we utilized the SYNAPSE VINCENT system (Fujifilm, Japan) to identify the kidney regions supplied by each renal artery, with the intention of clamping three arteries during the procedure (Figure 1C). Additionally, we examined the right ureter, which traversed through the anterior HSK. Subsequently, RAPN (da Vinci Xi system) was performed via a transperitoneal approach in the lateral position. An extra port was added to the standard RAPN setup to facilitate artery clamping (Figure 2A). As planned, we clamped the three arteries and confirmed the clamping using ultrasonography to ensure the blood flow around the tumor had ceased. This procedure closely followed the standard RAPN protocol previously described (8). The total operative time was 181 min, console time was 141 min, warm ischemic time was 14 min, and estimated blood loss was 100 ml. The patient was discharged on postoperative day three without any complications. Pathological examinations revealed clear-cell RCC, pT1a (Fuhrman grade 2) with negative surgical margins. Notably, follow-up CT at 53 months post-RAPN showed no recurrence or metastasis.

Figure 1. Computed tomography imaging findings in Case 1. (A) A three-dimensional image of the kidney, tumor, and renal arteries. (B) Enhanced computed tomography horizontal section in the early phase. (C) Multiple renal arteries no. 1-6, with the no. 4 artery area in light green, no. 5 in purple, and no. 6 in yellow. Thus, we planned to clamp arteries no. 1-3.

Figure 2. Port placement in robot-assisted partial nephrectomy. Case 1 (A) and Case 2 (B).

Case 2. A 45-year-old Japanese male with HSK presented to our Department with a renal tumor incidentally detected during a medical checkup. His medical history revealed spontaneous pneumothorax, but he had no relevant family history. Laboratory data and urine test results were largely within normal ranges. 3D-CT revealed HSK with three renal arteries and a 46 mm diameter tumor located on the isthmus. Using the SYNAPSE VINCENT system, we observed that the tumor was supplied by two renal arteries, one of which extended to the posterior region of the tumor (Figure 3A-C). The renal pelvises were bilaterally confluent and formed a ureter to the bladder (Figure 3D).

Figure 3. Computed tomography imaging findings in Case 2. (A) A three-dimensional image of the kidney, tumor, and renal arteries. (B) Enhanced computed tomography horizontal section in the early phase. (C) A three-dimensional image of the kidney: the left renal artery area is yellow. (D) A three-dimensional image of the collecting system.

The patient underwent RAPN (da Vinci Xi system) through a transperitoneal approach in the semi-lateral position. The port placement was adjusted to be lower than in standard RAPN because the tumor was located in the isthmus (Figure 2B). The surgery closely mirrored the standard RAPN procedure, with the tumor and upper artery easily identified after the mobilization of the duodenum. The second renal artery was located by carefully examining the inferior vena cava and tumor. After identifying the two arteries, we followed the standard RAPN protocol. Both renal arteries were effectively clamped, and the tumor was subsequently resected under warm ischemia after confirming the disappearance of blood flow using ultrasonography. The resection technique involved enucleation, with renal arteries clamped following the suturing of the resected bed. Closure of the renal parenchyma occurred after ensuring arterial hemostasis. The total operative time, console time, warm ischemic time and estimated blood loss were 177 min, 140 min, 31 min, and 34 ml, respectively. The patient was discharged on postoperative day three without any complications. Pathological examinations revealed clear-cell RCC and pT1b (Fuhrman grade 2) with negative surgical margins. Subsequently, follow-up CT at 13 months postoperatively showed no signs of recurrence or metastases.

Ethical approval. All procedures involving human participants were performed as per the ethical standards of the institutional and/or national research committee and the 1964 Helsinki declaration and its later amendments or comparable ethical standards (Institutional Review Board approval no. 5335).

Discussion

In this study, we presented the effectiveness of RAPN with selective artery clamping, which was achieved by assessing the blood flow distribution in each renal artery supplying the HSK.

RAPN has become the standard treatment for small renal tumors due to its lower perioperative complications and comparable functional and oncological outcomes to open partial nephrectomy (9). Consequently, RAPN is widely adopted in cases involving high complexity, hilar tumors, and chronic kidney diseases (3,4,10). However, there are limited reports on the use of RAPN for renal tumors in HSK cells due to the rarity and complexity of the vessels and collecting systems in such cases. To our knowledge, only seven cases of RAPN in patients with HSK have been reported (Table I) (11-17). The patients were within the age range of 19-84 years, with six males. The tumor size ranged from 15 to 46 mm in diameter. While two patients were treated via the retroperitoneal approach, others were managed via the transperitoneal approach. The choice of approach often depended on the tumor and renal artery location determined through preoperative 3D-CT. Notably, the tumor in Yamamichi et al.’s study was located on the anterior side, and they chose the retroperitoneal approach because the patient had a history of multiple abdominal surgeries (12). However, in this study, the transperitoneal approach was chosen for Case 1 because the tumor was located on the anterior side, and the patient had no surgical history. Specifically, two out of the nine cases, including ours, involved tumors in the isthmus. Sawada et al. reported a case of a 79-year-old female with a 45 mm renal tumor located on the isthmus of the HSK treated with RAPN. To ensure conformity with normal RAPN, they performed isthmus transection using a vessel sealer, which maintains the urinary tract’s integrity. Therefore, the patient’s and camera port positions were changed during surgery (16). In Case 2, although we were unable to cut the isthmus because the bilateral collecting systems were confluent, forming a single ureter, we successfully identified two renal arteries and resected the tumor by making the port placement lower than in standard RAPN. Notably, we observed that it is beneficial to confirm the area dominated by the renal arteries using the SYNAPSE VINCENT system (Fujifilm, Japan) before surgery, as we were able to plan the arteries to clamp, even with HSK involving multiple renal arteries, before performing the surgery. However, the ongoing debate regarding whether total or selective artery clamping technique is superior for RAPN remains (18). Nevertheless, in both our cases, we confirmed the cessation of blood flow around the tumor through intraoperative ultrasound after clamping the planned renal arteries, before initiating resection. Based on these results, we posit that using selective artery clamping methods with the SYNAPSE VINCENT system may lead to shorter operative times, reduced blood loss, and a lower risk of complications.

Table I. Previous case reports of robot-assisted partial nephrectomy in horseshoe kidney.

ccRCC: Clear-cell renal cell carcinoma; EBL: estimated blood loss; N/A: not available; RA: renal artery; RP: retroperitoneal; SDH: succinate dehydrogenase; TP: transperitoneal; WIT: warm ischemic time.

Consequently, when performing RAPN for HSK, it is important to assess patient-specific factors, such as surgical history, tumor location, and vascular and urinary tract anatomy, through 3D-CT.

Conclusion

We present two cases of renal tumors in patients with HSK who were successfully treated with RAPN without complications. Our findings suggest that RAPN with selective artery clumping methods may be a viable treatment approach for managing small renal tumors in patients with HSK when planning a surgical strategy based on the tumor location and vascular and urinary tract anatomies using preoperative 3D-CT.

Conflicts of Interest

All Authors have no conflicts of interest to declare in relation to this study.

Authors’ Contributions

YK wrote the article and provided the figures. KY contributed to the study design. YK, KY, TE, RM, HF, SM, JI, HI, and TT performed the RAPN and cared for the patients. All the Authors have read and approved the final article.