Renal hilar tumor with situs inversus- a case report and systematic review

Abstract

Total situs inversus is a rare congenital condition (1 in 25,000) with mirror-image organ positioning, complicating nephrectomies. A 68-year-old female with situs inversus presented with a right renal hilum mass incidentally discovered. Imaging revealed a tumor difficult to distinguish from the renal artery and an elongated right renal vein mimicking left-sided anatomy. Radical nephrectomy achieved favorable recovery and preserved renal function. Reviewing 14 cases (1987–2024), focus has shifted to anatomical variations, especially vascular anomalies, affecting surgical complexity. Preoperative imaging to assess adjacent structures is crucial for optimizing surgical approaches and ensuring patient safety.

1 Introduction

Situs inversus is a congenital autosomal recessive variation, characterized by a mirror-image reversal of internal organs compared to normal anatomical positioning, involving the heart, stomach, liver, spleen, and other organs 。The incidence of total situs inversus is estimated to range from 1 in 6500 to 1 in 25,000. Most patients are asymptomatic. However, situs inversus can present significant challenges in surgical procedures, especially when dealing with complex anatomical structures. Since the kidneys are paired organs located within the abdominal cavity, the impact of situs inversus on renal function is generally minimal, partial nephrectomy typically yields favorable outcomes for T1b renal cell carcinoma. However, hilar tumor, located near critical vascular structures such as the renal artery and vein, pose a higher degree of surgical difficulty. ^, Additionally, hilar tumors are an independent prognostic factor for recurrence following partial nephrectomy This paper presents a case of a patient with total situs inversus who was diagnosed with a hilar renal tumor and successfully underwent laparoscopic nephrectomy. Through a detailed account of this case, we explore the impact of situs inversus on surgical techniques and share clinical insights into the use of laparoscopic surgery for managing complex hilar renal tumors. We also reviewed all the published articles about patient underwent nephrectomy of renal cell carcinoma and situs inversus to understand the prognosis postoperatively.

2 Case report

A 68-year-old female patient was admitted to the hospital due to an incidental finding of a right renal mass during a hospital stay in the orthopedic department 10 days ago. The patient reports no discomfort, fever, pain, or hematuria. She has well-controlled hypertension for 20 years with metoprolol. No history of chronic illnesses or elevated blood glucose treatment.

Enhanced CT showed a right renal mass with associated hydronephrosis, located at the renal hilum, measuring approximately 63.30 × 52.07 mm, with clear margins and heterogeneous enhancement during the contrast phase. Imaging findings were consistent with a malignant renal tumor, staged as T1bN0M0. Multiple small cysts were observed in the left kidney, without any obvious masses. Angiography revealed that the inferior vena cava (IVC) was located to the left of the aorta, and the right renal vein was significantly longer than the left renal vein. The right ovarian vein drained into the right renal vein and then into the IVC ( Fig. 1 ). Preoperative renal function was good, with an eGFR-epi of 94.27 ml/min/1.73 m ² , right kidney GFR of 16.81 ml/min/1.73 m ² , and serum creatinine of 51.01 μmol/L. Cardiopulmonary function was normal, and after evaluation, a right nephrectomy was planned.

During operation, the right renal mass was found at the renal hilum, with dense adhesions to the surrounding fat and tissues. The IVC was located to the left, and the right renal vein was notably longer. The right ovarian vein traveled alongside the ureter and drained into the right renal vein before flowing into the IVC. Intraoperative blood loss was estimated at 220 ml, and the surgery lasted approximately 100 minutes. The resected specimen measured 10 x 6 × 5 cm, and the tumor was approximately 5 cm in diameter, located at the renal hilum. On postoperative day 5, the retroperitoneal drain was removed without any incidents.

On postoperative day 7, routine blood tests were normal, with an eGFR-epi of 83.93 ml/min/1.73 m ² and serum creatinine of 64.98 μmol/L, the patient has been discharged following a successful course of treatment. After the three-months follow-up, both eGFR-epi and serum creatinine were within normal ranges.

3 Discussions

Total situs inversus is a rare anatomical variation with an incidence of approximately 1 in 25,000. In nephrectomy procedures, its primary impact is on the identification and exposure of anatomical structures during surgery. In this case, we observed that the right renal vein was significantly elongated and received drainage from the right gonadal vein, a configuration typically seen in the left kidney of individuals with normal anatomy, which was also reported in other cases of situs inverse. ^, The tumor, located at the renal hilum, almost completely occupied this region, and imaging revealed that the tumor was difficult to distinguish from the renal artery. Under these circumstances, the risks of partial nephrectomy were high, and preoperative renal function assessment showed that the GFR of the right kidney was only 16.81 ml/min/1.73 m ² . Considering all factors, radical nephrectomy was deemed to provide the greatest benefit for the patient, as evidenced by postoperative recovery of renal function and changes in drainage output.

Despite the situs inversus causing the vascular distribution of the right kidney to resemble that of a normal left kidney, the anatomical structure is quite different from the normal mirrored arrangement, Anatomically, the right renal artery originates from the anterolateral aspect of the aorta, coursing to the right kidney posterior to the inferior vena cava, while the left renal artery arises from a slightly higher and more lateral position on the aorta, running almost horizontally to the left kidney. In our case of total situs inversus, despite the left renal artery originating from the anterolateral surface of the abdominal aorta and passing postero-inferior aspect of the inferior vena cava and renal vein towards the left kidney, and the right renal artery arising from a more lateral position on the aorta and running horizontally to the right kidney, the left renal artery arises at a higher level than the right, which is consistent with the typical anatomical pattern in normal individuals ( Fig. 2 ). However, a case also reported that the left renal artery being positioned lower than the right renal artery.

The heights of the renal hila and the upper poles of both kidneys were nearly identical, although the tumor may have caused the lower pole of the right kidney to be slightly lower than that of the left kidney. This finding contradicts the traditional anatomical view that the right kidney is generally positioned lower due to pressure from the liver. Further basic research may be needed to explore this phenomenon. Additionally, the longer right renal vein and its greater distance from the diaphragm likely made surgical mobilization and resection of the kidney easier.

According to our literature review, from 1987 to 2024, 14 cases of situs inversus patients with renal cell carcinoma undergoing nephrectomy have been reported previously ( Table 1 ). Of these, 5 involved the right kidney, and 9 the left; 6 were laparoscopic, while 8 were open surgeries. Blood loss was reported in only 3 cases, showing considerable variation. One report described a robot-assisted partial nephrectomy for a T1b renal hilar tumor, but long-term follow-up data is lacking, further studies are needed to assess the long-term safety of this approach.

Table 1

Cases with situs inversus undergoing nephrectomy for renal cell carcinoma.

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