The horseshoe kidney: Surgical anatomy and embryology

Expression of Congenital Anomalies of the Kidney and Urinary Tract (CAKUT) Candidate Genes EDA2R, PCDH9, and TRAF7 in Normal Human Kidney Development and CAKUT

Approximately half of the cases of chronic kidney disease (CKD) in childhood are caused by congenital anomalies of the kidney and urinary tract (CAKUT). Specific genes were identified as having significant importance in regard to the underlying genetic factors responsible for the CAKUT phenotype, and in our research, we focused on analyzing and comparing the expression levels of ectodysplasin A2 receptor (EDA2R), protocadherin9 (PCDH9), and TNF receptor-associated factor 7 (TRAF7) proteins in the cortex and medulla of healthy control kidneys during developmental phases 2, 3, and 4. We also performed an analysis of the area percentages of the mentioned proteins in the cortical and medullary sections of healthy embryonic and fetal kidneys compared to those affected by CAKUT, including duplex kidneys (DK), horseshoe kidneys (HK), hypoplastic kidneys (HYP), and dysplastic kidneys (DYS). We found that the CAKUT candidate gene proteins EDA2R, PCDH9, and TRAF7 are all expressed during normal human kidney development stages. In DYS, the expression of EDA2R was higher than in normal kidneys, likely due to EDA2R's role in apoptosis, which was upregulated in specific cases and could possibly contribute to the formation of DYS. The expression of PCDH9 was lower in HK, which can be attributed to the possible role of PCDH9 in cell migration suppression. Decreased PCDH9 expression is linked to increased cell migration, potentially contributing to the development of HK. The level of TRAF7 expression was reduced in all examined kidney disorders compared to normal kidneys, suggesting that this reduction might be attributed to the crucial role of TRAF7 in the formation of endothelium and ciliogenesis, both of which are essential for normal kidney development. Further research is required to ascertain the function of these proteins in both the typical development of the kidney and in CAKUT.

Horseshoe kidney: Morphologic features, embryologic and genetic etiologies, and surgical implications

The horseshoe kidney (HSK) is the most common congenital abnormality of the upper urinary tract with an incidence of approximately 1 in 500 in the general population. Although individuals with HSK are often asymptomatic, they are at increased risk for neoplasms, infections, ureteropelvic obstruction secondary to lithiasis or vascular compression. Direct injury from trauma is increased in these individuals as is the risk of intraoperative complications secondary to damage involving the typically complex renal or adrenal vascular supply. We briefly review etiological factors including renal and urinary system embryology, genetic mutations, abnormalities related to faulty cell signaling, aberrant cell migration, and other possible causes including environmental exposures and trauma. In addition, we call attention to factors that might influence the success of surgical procedures in patients with HSK. We argue that an understanding of possible etiologies of the HSK and its different subtypes may be useful when planning surgical procedures or considering risk-benefit ratios associated with different surgical options. We briefly present the organization of a HSK in a 100-year-old male demonstrating an unusual vascular supply discovered during a dissection laboratory session in a medical school anatomy course. We describe the structure of the HSK, the position and relationships of the HSK to other structures within the abdomen, and the associated vascular relationships.

Implications of Tumor Surgery in Horseshoe Kidneys: A Comparative Study of Outcomes and Surgical Practices

OBJECTIVE

To contrast surgical outcomes of Horseshoe Kidney (HSK) patients with localized renal masses suspected of cancer with nonfused nonectopic kidney patients, emphasizing safe surgical practices for HSKs.

METHODS

The study examined solid tumors from the Mayo Clinic Nephrectomy registry between 1971 and 2021. Each HSK case was matched to three non-HSK patients based on various factors. The outcomes measured included complications within 30days of surgery, change in estimated glomerular filtration rate, and overall, cancer-specific, and metastasis-free survival rates.

RESULTS

Thirty of the 34 HSKs had malignant tumors compared with 90 of the 102 patients in the nonfused nonectopic referent cohort. Accessory isthmus arteries were present in 93% of HSK cases, with 43% exhibiting multiple arteries and 7% with 6 or more arteries. Estimated blood loss and surgery duration were significantly higher in HSKs (900 vs 300 mL, P = .004; 246 vs 163 minutes, P < .001, respectively). The HSK group demonstrated an overall complication rate of 26% (vs 17% in referents, P = .2) and a median change in estimated glomerular filtration rate at 3months of - 8.5 (vs -8.1 in referents, P = .8). At 5-year follow-up, survival rates for HSK patients were 72%, 91%, and 69% for overall, cancer-specific, and metastasis-free survival, respectively. The corresponding rates were 79%, 86%, and 77%, respectively, for matched referent patients (P > .05).

CONCLUSION

HSK tumor management is technically challenging with higher blood loss; however, the data demonstrate comparable outcomes for patients with HSK tumors, including complications and survival, to those without HSKs in experienced centers.

Bilateral Wilms tumor in a patient with a horseshoe and duplex kidney: A case report

The occurrence of horseshoe kidney with duplex urinary collecting systems is rare. Herein, we report a case of bilateral Wilms tumor (BWT) in a patient with a concurrent horseshoe kidney and left duplex kidney, which had not been previously reported. The patient was treated with neoadjuvant chemotherapy, followed by surgical resection and adjuvant chemotherapy. The tumor recurred 6 months postoperatively. A second resection was performed, followed by the administration of chemotherapy and radiotherapy. The patient passed away 15 months after the initial diagnosis of BWT.

Horseshoe Kidney: 500 Years From the First Report in the Literature

Horseshoe kidney or ren arcuatus is the most common renal fusion anomaly, with an incidence of 1:500 in the normal population and a male predominance of 2:1. In >90% of cases, the fusion occurs along the inferior pole. It may vary in location, orientation, and arterial and venous anatomy. In 1522, Berengario da Carpi described this renal malformation for the first time in his masterpiece "Isagogae breves" (Introduction to Anatomy). He reported the results of a postmortem examination in the public autopsy room of the University of Bologna, describing "kidneys that are continuous as if they were a kidney, with two emulsifying veins, two emulsifying arteries, two ureteral outlets." In 1564, Leonardo Botallo described and illustrated the features of this atypical anatomical representation, and later, in 1602, Leonard Doldius added further details by examining this anatomical feature during an autopsy. In 1761, Giovanni Battista Morgagni discussed this condition not only as a rare anatomical curiosity found only in necroscopy but also discussed its physiological aspect. In the nineteenth century, with the advent of renal surgery, the horseshoe kidney played a more important role in urological diagnosis and treatment, and its identification became more frequent. With the advent of pyelography, imaging reports of the horseshoe kidney allowed a more accurate representation of the anatomical variants, which was particularly useful in preoperative assessment and outcomes. Berengario da Carpi laid the foundation for a better knowledge of this anatomical anomaly. Five hundred years after the first report in the literature, relevant advances have been made in the management of complications associated with horseshoe kidney and in diagnosis, confirming the need to monitor individuals with this condition who are at higher risk of developing chronic kidney disease.

FOXD1 is required for 3D patterning of the kidney interstitial matrix

BACKGROUND

The interstitial extracellular matrix (ECM) is comprised of proteins and glycosaminoglycans and provides structural and biochemical information during development. Our previous work revealed the presence of transient ECM-based structures in the interstitial matrix of developing kidneys. Stromal cells are the main contributors to interstitial ECM synthesis, and the transcription factor Forkhead Box D1 (Foxd1) is critical for stromal cell function. To investigate the role of Foxd1 in interstitial ECM patterning, we combined 3D imaging and proteomics to explore how the matrix changes in the murine developing kidney when Foxd1 is knocked out.

RESULTS

We found that COL26A1, FBN2, EMILIN1, and TNC, interstitial ECM proteins that are transiently upregulated during development, had a similar distribution perinatally but then diverged in patterning in the adult. Abnormally clustered cortical vertical fibers and fused glomeruli were observed when Foxd1 was knocked out. The changes in the interstitial ECM of Foxd1 knockout kidneys corresponded to disrupted Foxd1+ cell patterning but did not precede branching dysmorphogenesis.

CONCLUSIONS

The transient ECM networks affected by Foxd1 knockout may provide support for later-stage nephrogenic structures.

Laparoscopic nephron-sparing surgery for horseshoe kidney complicated with renal hemangioma: a case report and literature review

In very rare cases, horseshoe kidney can present simultaneously with renal hemangioma. Nephron-sparing surgery (NSS) is a minimally invasive surgical procedure for horseshoe kidney with tumor, but it is difficult to operate and has not been reported. We report a 71-year-old female with imaging examination revealed an unexpected horseshoe kidney malformation and a cystic mass in the right kidney before her bladder cancer surgery. After one and a half years of follow-up, the mass was progressively enlarged, and was classified as Bosniak type III. After evaluating the anatomical structure around the lesion by 3D reconstruction computed tomography, she received cystoscopic right double J ureteral catheter placement combined with retroperitoneal laparoscopic partial nephrectomy of the right kidney. After a 3-month follow-up, no tumor recurrence was observed, with normal kidney function. Retroperitoneal laparoscopic NSS of horseshoe kidney with hemangioma is feasible and adequate preoperative 3D reconstruction imaging is the guarantee of safe and smooth operation.

Robotic-assisted laparoscopic pyelolithotomy with intracorporeal pyeloscopy in a horseshoe kidney

Horseshoe kidneys are one of the most common congenital genitourinary malformations and can increase the complexity of common urologic procedures, especially nephrolithiasis. We present a patient who underwent robotic-assisted laparoscopic pyelolithotomy with intracorporeal pyeloscopy and stone basketing to treat a left lower pole stone burden located in a horseshoe kidney. This procedure provided benefits of expanded maneuverability, dexterity, and stability, which resulted in successful elimination of stone burden on post-operative imaging. We believe that robotic-assisted laparoscopic pyelolithotomy with intracorporeal pyeloscopy should be considered as a treatment option in similar cases of complicated nephrolithiasis due to complex renal anatomy.

Pure laparoscopic radical nephroureterectomy for complicated renal pelvis carcinoma combined with horseshoe kidney: A case report and literature review

We reported a case of pure laparoscopic radical nephroureterectomy for complicated renal pelvis carcinoma combined with horseshoe kidney (HSK). The aim was to present a case report and review of the literature about renal pelvis carcinoma combined with HSK. The case report includes a history of patient data. The pure laparoscopic radical nephroureterectomy was provided with the informed consent of the patient. A 53-year-old patient was diagnosed with a right renal pelvis mass with HSK. We performed laparoscopic radical nephroureterectomy with partial cystectomy and horseshoe renal isthmus amputation. Histopathological features, computed tomography urography (CTU), and angiography (CTA) confirmed the diagnosis of renal pelvis carcinoma combined with HSK. The tumor was removed, and the patient had an uneventful recovery. Renal pelvis carcinoma combined with HSK is a rare case. Due to severe anatomical abnormalities, this disease is a major challenge for urologists. We share our successful case for readers to learn from.

State of the Science for Kidney Disorders in Phelan-McDermid Syndrome: UPK3A, FBLN1, WNT7B, and CELSR1 as Candidate Genes

Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder caused by chromosomal rearrangements affecting the 22q13.3 region or by SHANK3 pathogenic variants. The scientific literature suggests that up to 40% of individuals with PMS have kidney disorders, yet little research has been conducted on the renal system to assess candidate genes attributed to these disorders. Therefore, we first conducted a systematic review of the literature to identify kidney disorders in PMS and then pooled the data to create a cohort of individuals to identify candidate genes for renal disorders in PMS. We found 7 types of renal disorders reported: renal cysts, renal hypoplasia or agenesis, hydronephrosis, vesicoureteral reflux, kidney dysplasia, horseshoe kidneys, and pyelectasis. Association analysis from the pooled data from 152 individuals with PMS across 22 articles identified three genomic regions spanning chromosomal bands 22q13.31, 22q13.32, and 22q13.33, significantly associated with kidney disorders. We propose UPK3A, FBLN1, WNT7B, and CELSR1, located from 4.5 Mb to 5.5 Mb from the telomere, as candidate genes. Our findings support the hypothesis that genes included in this region may play a role in the pathogenesis of kidney disorders in PMS.

Lower pole anatomy of horseshoe kidney and complete ureteral duplication: Anatomic and radiologic study applied to endourology

Purpose:

To analyze the 3-dimensional intrarenal anatomy of horseshoe kidneys (HK) and kidney with complete ureteral duplication (CUD), in polyester resin endocasts of the collecting system and in patients submitted to 3D computerized tomography scan (CT-scan).

Materials and Methods:

We analyzed seven 3-dimensional polyester resin endocasts of the kidney collecting system obtained from 6 fresh adult cadavers (4 with unilateral CUD and 2 with horseshoe kidney) and CT-scan reconstruction images of kidneys from 24 patients: 6 patients with HK, 8 with CUD and 10 patients without renal anomalies that were used as controls. We analyzed the spatial distribution of the calices, the infundibula diameters, the angle between the lower infundibulum and the renal pelvis (LIP) and the angle between the lower infundibulum and the inferior minor calyces (LIICA). Measurements of the width and length of the inferior infundibulum and the infundibula of the minor calyces, as well as the angles (LIP and LIICA) were made with the aid of the LibreOffice 6.3 software. The data were analyzed with the IBM^® SPSS^® Statistics.

Results:

There was no statistical difference in the inferior pole measurements between the groups with anomalies and the control group, both in polyester resin endocasts and CT-scan reconstruction images for LIP. When we compared the LIP in the CT-scan between HK versus CUD (p= 0.003), and HK versus the control group (p= 0.035), we observed statistical difference.

Conclusions:

The knowledge of spatial anatomy of lower pole is of utmost importance during endourologic procedures in patients with kidney anomalies. In the present study we observed that horseshoe kidneys had more restrictive anatomic factors in lower pole than the complete ureteral duplication.

Open surgical repair of abdominal aortic aneurysm and horseshoe kidney: A strange relationship

Introduction and importance

The horseshoe kidney (HK) is the most common fusion defect of the kidneys. Τhe simultaneous presence of HK and abdominal aortic aneurysm (ΑΑΑ) is rare and comprises a technical challenge for the vascular surgeon due to variation of renal arteries and the renal isthmus overlying the AAA sac.

Case presentation

We present the first case in Nicosia General Hospital of Cyprus of an infrarenal AAA with a HK (Crawford Type I), which was successfully treated using an open surgical approach.

Clinical discussion

Review the technical challenges associated with the case and a brief reference to the relevant published articles.

Conclusion

The surgical repair of coexistence of AAA and HK continues to be a difficult technical challenge for the vascular surgeon from the past until today. There is a need to record the few cases and to create detailed specific guidelines to facilitate the surgical approach for the disease.

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Τhe simultaneous presence of HK and abdominal aortic aneurysm (ΑΑΑ) is rare.

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It comprises a technical challenge for the vascular surgeon.

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First case in Cyprus of an infrarenal AAA with a HK.

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The preoperative planning for the coexistence of the HK and AAA is important and useful.

Bilateral En-Block Horseshoe Kidney Laparoscopic Nephrectomy

Horseshoe kidney (HSK) has a prevalence of 1 in every 500 individuals. The management of patients with HSK is usually conservative, except in the presence of symptoms such as obstruction, stones, glomerulopathies, and tumors. In the following case report, we describe how a bilateral en-block transmesenteric laparoscopic nephrectomy in supine position was performed.

A 5-year-old boy, with proximal hypospadias and early onset of chronic kidney disease due to focal segmental glomerulosclerosis on biopsy, underwent a genetic molecular evaluation that confirmed a pathogenic mutation at the WT-1 gene. Due to the increased risk of developing Wilms tumor, he underwent a bilateral transmesenteric nephrectomy.

In a five-minute video, we describe how we performed an en-block transperitoneal and transmesenteric laparoscopic nephrectomy with special attention to patient positioning, including the feasibility of performing the dissection of the left renal hilum and isthmus with the patient in supine with no need for repositioning, and then moving to the dissection of the right renal hilum and completion of the procedure.

The case herein reported enables us to describe the technical key-points to perform a bilateral en-block laparoscopic nephrectomy with shorter operative time and reduction of blood loss by preserving the entire specimen, without the need for an isthmus transection.

Diagnosis, Management, and Challenges in Synchronous Bilateral Wilms Tumor in a Horseshoe Kidney: A Case Report

Horseshoe kidney (HK) refers to a congenital malformation that results from fusion of both the kidneys at one pole, and is the most common renal fusion defect with an incidence of 1 in 400 to 600 individuals. Synchronous bilateral development of Wilms tumor (WT) in an HK is extremely rare. Here, we present a case of synchronous bilateral WT in an HK in an 18-month-old girl. The patient received 12 weeks of preoperative chemotherapy followed by 2-step surgical resection including nephron-sparing surgery (NSS) in both kidneys and left nephrectomy because of positive surgical margin and adjuvant chemotherapy. The patient is still in remission and asymptomatic 6 months after the completion of treatment. In this report, we discuss the treatment modalities of synchronous bilaterally located WT in HK. We conclude that successful outcomes can be obtained with preoperative chemotherapy and NSS in such cases even in the presence of advanced disease and complex anatomic conditions. In addition, the deepest tumor point can be reached during NSS, but total nephrectomy should be considered regarding the possibility of microscopic residue.

OUP accepted manuscript

A 76-year-old gentleman with a background of benign prostatic hyperplasia, hiatus hernia and anxiety was referred to the rapid access haematuria service following an episode of painless visible haematuria. Flexible cystoscopy did not reveal any concerning bladder lesions. CT Urogram demonstrated a horseshoe kidney with a filling defect in the left upper pole moiety suspicious for an urothelial carcinoma. The patient was subsequently referred to the urology services in a tertiary centre. Flexible ureterorenoscopy was performed, with findings of a likely urothelial carcinoma corresponding to the suspicious area on imaging. Biopsy of this lesion revealed a low grade urothelial cancer. The patient proceeded to have a laparoscopic left heminephroureterectomy with an open bladder cuff. The patient recovered well and urinary catheter was removed Day 12 post procedure after the performance of a cystogram. Histology revealed a favourable pTa low grade malignancy, and the patient will require ongoing follow-up moving forward. This case report highlights the operative intricacies in managing patients with horseshoe kidney due to anatomic variations associated with this condition.

Endovascular Aneurysm Repair for a Patient with Horseshoe Kidney and the Importance of Watershed Sign and Volumetry by Preoperative Contrast-Enhanced Computed Tomography

We report a case of endovascular aneurysm repair (EVAR) in a patient with horseshoe kidney (HSK) in whom preoperative contrast-enhanced (CE) computed tomography (CT) showed watershed sign. This sign enabled prediction of postoperative renal function by accurate renal volumetry. A 75-year-old man with HSK and a 59-mm abdominal aortic aneurysm was referred for treatment. Preoperative CECT showed watershed lines at the margin of the isthmus, which was perfused by the accessory renal arteries. Using this sign, we calculated the accurate volume of the isthmus, which was 24.5% of the total parenchyma. EVAR was safely performed without renal dysfunction.

Advanced-stage Wilms tumor arising in a horseshoe kidney of a 9-year-old child: a case report

BACKGROUND

Horseshoe kidney (HK) is one of the most common renal fusion abnormalities, with an incidence of 1:400 in the normal population. However, Wilms tumor (WT) arising in an HK is a rare occurrence. We report the case of a 9-year-old boy who presented with an advanced WT in an HK and also highlight the management challenges in a resource-poor setting such as ours.

CASE PRESENTATION

The patient was a 9-year-old Nigerian boy presented to the Pediatrics Outpatient Clinic of the University of Maiduguri Teaching Hospital (UMTH) with a history of progressive abdominal swelling, weight loss, abdominal pain, and cough. Abdominal examination revealed an irregular, firm, and non-tender mass in the right lumbar region. A computed tomography (CT) scan of the abdomen showed a heterogeneously dense mass that was predominantly to the right side of the abdomen and crossed the midline to the left side, where it continued with the relatively normal renal tissue. Chest CT revealed pulmonary metastases. A diagnosis of WT in an HK was made. The patient had a 6-week course of neoadjuvant chemotherapy, and a right nephrectomy and left partial nephrectomy was performed. The final histologic diagnosis of WT was made. Radiotherapy was intended but was not available in our facility, and the parents could not afford referral to another center.

CONCLUSIONS

Children with a clinically suspected HK with WT should undergo a careful imaging evaluation such as CT before any surgical intervention. Neoadjuvant chemotherapy to reduce tumor bulk might be a good treatment method to reduce surgical morbidity and aid in complete excision and potential for preserving renal function.

Unveiling the confusion in renal fusion anomalies: role of imaging

Renal fusion anomalies are common congenital anomalies of the urogenital tract and have their genesis in the early embryonic period. They are classified into partial fusion anomalies (e.g., crossed fused ectopia, and horseshoe kidney) and complete fusion anomalies (e.g., fused pelvic kidney). Horseshoe kidney is the most common renal fusion anomaly and is characterized by the presence of two distinct functioning kidneys on either side of the vertebral column, with fusion occurring at the inferior poles in majority of the cases. Crossed fused ectopia is characterized by the presence of an ectopic kidney that crosses the midline and fuses with the orthotopic contralateral kidney, whereas fused pelvic (pancake) kidney is a complete fusion anomaly characterized by extensive medial fusion of both kidneys in the pelvis. Fusion anomalies are often associated with abnormalities of renal rotation, migration, and vascular supply, which predispose the kidneys to a number of complications and create difficulty during retroperitoneal surgeries and interventions. They are also associated with other congenital abnormalities of the urogenital tract, gastrointestinal tract, cardiovascular system, and skeletal system. Hence, a thorough understanding of the etiopathogenesis and radiological features of fusion anomalies is important for directing patient management. This review summarizes the embryological basis, clinical presentation and imaging approach to renal fusion anomalies, followed by detailed anatomical and radiological description of the morphological types, and the complications associated with these anomalies.

Horseshoe kidney with PLA2R-positive membranous nephropathy

Background

Horseshoe kidney (HSK) is a common congenital defect of the urinary system. The most common complications are urinary tract infection, urinary stones, and hydronephrosis. HSK can be combined with glomerular diseases, but the diagnosis rate of renal biopsy is low due to structural abnormalities. There are only a few reports on HSK with glomerular disease. Here, we have reported a case of PLA2R-positive membranous nephropathy occurring in a patient with HSK.

Case presentation

After admission to the hospital due to oedema of both the lower extremities, the patient was diagnosed with nephrotic syndrome due to abnormal 24-h urine protein (7540 mg) and blood albumin (25 g/L) levels. Abdominal ultrasonography revealed HSK. The patient’s brother had a history of end-stage renal disease due to nephrotic syndrome. Therefore, the patient was diagnosed with PLA2R-positive stage II membranous nephropathy through renal biopsy under abdominal ultrasonography guidance. He was administered adequate prednisone and cyclophosphamide, and after 6 months of treatment, urinary protein excretion levels significantly decreased.

Conclusion

The risk and difficulty of renal biopsy in patients with HSK are increased due to structural abnormalities; however, renal biopsy can be accomplished through precise positioning with abdominal ultrasonography. In the literature, 20 cases of HSK with glomerular disease have been reported thus far. Because of the small number of cases, estimating the incidence rate of glomerular diseases in HSK is impossible, and the correlation between HSK and renal pathology cannot be stated. Further studies should be conducted and cases should be accumulated to elucidate this phenomenon.

Surgical management of horseshoe kidney tumors. Literature review and analysis of two cases

INTRODUCTION

The horseshoe kidney is a rare congenital anomaly in the general population that combines renal ectopia, malrotation and abnormal vascular supply. The most frequently developed tumor in this case is renal cell carcinoma (50%). One of its main characteristics is great anatomical variation, especially in terms of vascular structures.

MATERIAL AND METHODS

We present two cases of patients with diagnosis of renal tumor in horseshoe kidneys, both treated with laparoscopic partial nephrectomy in our department. Additionally, we have carried a review of the current literature.

DISCUSSION

Indications for surgical treatment in this pathology are the same as in kidneys with normal anatomy. Traditionally, treatment has been open surgery, with heminephrectomy as surgery of choice. The current trend is to advocate nephron-sparing surgery, and the laparoscopic approach has been progressively gaining importance.

CONCLUSION

A thorough imaging study is essential for proper surgical planning.

Wilms' Tumor in Horseshoe Kidney

Wilms' tumor is the most common malignant kidney tumor found in children. The Horseshoe kidney is the most common renal fusion malformation. However, Wilms' tumor is rarely identified in horseshoe kidney patients. Multimodal treatments in Wilms' tumor can play important roles in increasing the survival rate. In this study, we report the case of a 6-year-old boy in whom a Wilms' tumor was identified in a horseshoe kidney. The tumor was successfully treated with preoperative chemotherapy, followed by surgical resection.

Surgical management of horseshoe kidney tumors. Literature review and analysis of two cases

INTRODUCTION

The horseshoe kidney is a rare congenital anomaly in the general population that combines renal ectopia, malrotation and abnormal vascular supply. The most frequently developed tumor in this case is renal cell carcinoma (50%). One of its main characteristics is great anatomical variation, especially in terms of vascular structures.

MATERIAL AND METHODS

We present two cases of patients with diagnosis of renal tumor in horseshoe kidneys, both treated with laparoscopic partial nephrectomy in our department. Additionally, we have carried a review of the current literature.

DISCUSSION

Indications for surgical treatment in this pathology are the same as in kidneys with normal anatomy. Traditionally, treatment has been open surgery, with heminephrectomy as surgery of choice. The current trend is to advocate nephron-sparing surgery, and the laparoscopic approach has been progressively gaining importance.

CONCLUSION

A thorough imaging study is essential for proper surgical planning.

Malformative Reno-Urinary Pathology in Patients with HIV Infection-Clinical and Therapeutic Implications

Chronic kidney disease is an important comorbidity of HIV infection causing real problems in the evolution and medical healthcare of HIV-positive patients. In recent years, a significant number of HIV-positive patients develop renal dysfunction, several mechanisms being incriminated: direct effect of the virus, toxic effect secondary to of antiretroviral medication, secondary to associated comorbidities, given that life expectancy has increased significantly in the last decade, thanks to the use of antiretroviral therapies. There are few studies in the literature to evaluate malformative renourinary pathology in patients with HIV infection. We present the case of a patient with HIV infection, horseshoe kidney, chronic kidney disease and incomplete Fanconi syndrome, secondary to the administration of tenofovir fumarate, a nucleoside reverse transcriptase inhibitor. Malformations, abnormalities or dysmorphysms of the renal tract should be considered in the HIV-positive patient with secondary renal dysfunction because they take a wide range of forms, are underdiagnosed and predispose to multiple complications, with varying degrees of severity, such as urinary tract infections, renal stones or progression of chronic kidney disease. Tenofovir fumarate and atazanavir must be avoided in patients with HIV infection and chronic renal dysfunction.

Bilateral pelvic kidneys with upper pole fusion and malrotation: a case report and review of the literature

BACKGROUND

The incidence of ectopic kidneys is 1:12,000 clinically and 1:900 postmortem. Patients with pelvic mal-rotated kidneys are more susceptible to recurrent urinary tract infections, recurrent renal stones, and renal injury. Fusion of the kidney lower poles is relatively common compared to other types of renal anomalies.

CASE PRESENTATION

We present the case of a 36-year-old Sudanese female patient who presented with a long history of recurrent urinary tract infections unresponsive to antibiotics. Ultrasound scan revealed bilateral pelvic kidneys. Computed tomography (CT) urography confirmed bilateral ectopic fused kidneys, with the left kidney mal-rotated (renal pelvis facing upwards and laterally). Kidney infection secondary to vesicoureteral reflux was diagnosed. Antibiotics were prescribed according to culture and sensitivity. The patient responded well to ciprofloxacin.

CONCLUSION

A history of recurrent urinary tract infections without an apparent cause is highly suggestive of renal anomaly and should be investigated expediently. Ultrasonography or CT imaging may be utilized to aid in diagnosis. Early recognition may help prevent the high risk of end-stage renal failure associated with anomalies.

Renal outcomes in adult patients with horseshoe kidney

BACKGROUND

Horseshoe kidney (HSK) is a congenital disorder that is usually asymptomatic, but that increases the risks of kidney stones and infectious disease. However, renal outcomes such as end-stage renal disease (ESRD) in patients with HSK remain unclear.

METHODS

In total, 146 patients with HSK (age of ≥20 years) from two tertiary hospitals were included in this study. Control individuals who underwent medical check-ups were selected by matching for age, sex, serum creatinine level, hypertension and diabetes. The hazard ratios (HRs) for the risks of ESRD and all-cause mortality were calculated after adjustment for multiple variables.

RESULTS

The proportions of HSK-related complications for obstruction, kidney stones, urinary tract infection and urogenital cancer were 26, 25, 19 and 4%, respectively. During the median follow-up period of 9 years (maximum 32 years), the incidence of ESRD was 2.6/10 000 person-years. The risk of ESRD in patients with HSK was higher than in control individuals [adjusted HR = 7.6; 95% confidence interval (CI) 1.14-50.47]. All-cause mortality did not differ between the two groups (adjusted HR = 0.6; 95% CI 0.08-4.29).

CONCLUSIONS

Patients with HSK are at risk of ESRD, which may be attributable to the high prevalence of complications. Accordingly, these patients should be regarded as having chronic kidney disease and require regular monitoring of both kidney function and potential complications.

Fenestrated endovascular abdominal aortic aneurysm repair with concomitant horseshoe kidney

Horseshoe kidney, representing abnormal fusion of the inferior renal poles, is a rare anatomic anomaly posing challenges in the setting of surgical abdominal aortic aneurysm repair. Historically, open repair has been the favoured surgical approach. However, due to the location of the renal isthmus and wide-ranging variation in anomalous renal vasculature, endovascular aneurysm repair (EVAR) has emerged as a popular, less invasive alternative. We describe one of the first published cases of two-fenestration EVAR in a patient with concomitant horseshoe kidney, followed by a discussion of current trends in surgical management. With the increasing availability to customise fenestrated grafts to patients' unique anatomy, this advanced EVAR technique may emerge as the preferred approach in certain cases.

Laparoscopic resection for low rectal cancer in a patient with horseshoe kidney - Technical considerations to prevent iatrogenic injuries

Horseshoe kidney (HSK) is a rare congenital malformation of the kidneys and is commonly associated with other anomalies of the renovascular and ureteropelvic systems. These anomalies present a surgical challenge, especially for surgeries involving the retroperitoneum. We present the case of a 56-year-old male patient with biopsy-proven rectal cancer who had completed neoadjuvant chemoradiation and was planned for curative resection. Contrast-enhanced computed tomography (CECT) of the abdomen and pelvis revealed the presence of an HSK. Reconstructed three-dimensional (3D) images of the renal vasculature revealed the presence of an accessory renal artery originating directly from the aorta and supplying the isthmus of the HSK without any other venous or ureteral anomalies. Laparoscopic abdominoperineal resection with total mesorectal excision was done without any untoward complications. The presence of HSK per se is not a contraindication for laparoscopic operations involving the retroperitoneum. Pre-operative 3D CECT helps to identify the presence of anatomical variations and guides surgical resection.

Presacral Anatomy in Women With a Horseshoe Kidney

OBJECTIVE

Horseshoe kidney (HSK) is the most common renal fusion defect that can alter vascular and upper urinary tract anatomy. Anatomic variations in the presacral space can make surgical dissection very challenging. The aim of this study was to characterize presacral anatomy in women with HSK.

METHODS

Large academic centers' database was queried to identify imaging studies in adult women with HSK. Available multiplanar computed tomography and magnetic resonance imaging images were reviewed, and relevant vascular and upper urinary tract anatomy was measured and compared with published normal values. Study population was compared with the normal controls using Student t test, χ test, or Fisher exact test as appropriate.

RESULTS

One hundred seventy-eight women were identified initially, and 20 confirmed to have HSK on imaging. The mean ± SD age was 54.5 ± 16.9 years, and body mass index was 27.3 ± 7.5 kg/m. Women with HSK had a narrower angle of aortic bifurcation (39.1 ± 18.7 degrees vs 55.6 ± 4.5 degrees, P = 0.014); the right ureter was closer to midline (22.9 ± 8.8 mm vs 32.3 ± 1.2 mm, P < 0.001) when compared with normal controls anatomy. In 40% of women with HSK, the bifurcation of the vena cava was below the level of L5 in contrast to the 8% in the normal population (P < 0.001). In 60% of women with HSK, the inferior pole of the kidney was at or below L5.

CONCLUSIONS

Ureteral, renal, and vascular anatomic alterations in women with HSK may make presacral surgical anatomy challenging by obscuring the anterior longitudinal ligament anchoring point. Preoperative imaging is warranted to determine the feasibility of female pelvic reconstructive surgery in HSK patients.

Coexistence of a rare type of ectopic kidney with atypical renal vasculature

Knowledge of anatomical anomalies is significant for all specialists in clinical practice and may prevent serious complications following medical procedures. This report presents the rare crossed fused renal ectopia (CFRE) with atypical renal vasculature in cadaver of a 68-year-old man. The ectopic kidney was located on right side with four renal veins, three renal arteries, two ureters, where one of them is double. The embryological background, as well as the potential clinical significance of this morphological variation, is discussed. An interventional radiological and surgical procedure should be appropriately implemented to treat anomalies of vessels and CFRE.

Best strategy in managing the association of Horse-shoe-Kidney and Abdominal Aortic Aneurysm: Case report

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Most common renal anomalies.

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Rare association of Horse-Shoe-kidney and Abdominal aortic aneurysm.

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Special challenge in managing this pathology given the close spatial relationship.

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Frequent renal arterial variation.

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Surgery or endovascular treatment.

Introduction

Horseshoe Kidney (HSK) is probably the most common of all renal fusion abnormalities. However the association of Abdominal aortic aneurism (AAA) and HSK is rare, and occurred in 0,12% of patient affected by AAA.

Presentation of case

We present a patient with the concomitant presence of AAA and HSK treated by open surgical repair with a transperitoneal approach without section of the isthmus with great outcomes after surgery.

Discussion

The management of AAA associated with HSK presents a special challenge during vascular surgery, given the close spatial relationship and the frequent renal arterial variations that accompanies HSK.

Conclusion

Diagnosis and a well designed surgical strategy are required to avoid surgical post operative complications.

A Horseshoe Kidney With Solid Mass: A Case Report

Sonography can be used to detect horseshoe kidneys. Sonographic findings for horseshoe kidney commonly include an isthmus connection occurring anterior to the aorta and just inferior to the inferior mesenteric artery. This anomaly can occur with or without complications. Each kidney is associated with its separate collecting system, leading to increased risk for complications. This case study describes the importance of identifying a horseshoe kidney, isthmus, and blood supply to ensure prompt intervention if needed. A case report of a horseshoe kidney with a solid mass, in the isthmus, is provided.

Rare heterozygous GDF6 variants in patients with renal anomalies

Although over 50 genes are known to cause renal malformation if mutated, the underlying genetic basis, most easily identified in syndromic cases, remains unsolved in most patients. In search of novel causative genes, whole-exome sequencing in a patient with renal, i.e., crossed fused renal ectopia, and extrarenal, i.e., skeletal, eye, and ear, malformations yielded a rare heterozygous variant in the GDF6 gene encoding growth differentiation factor 6, a member of the BMP family of ligands. Previously, GDF6 variants were reported to cause pleiotropic defects including skeletal, e.g., vertebral, carpal, tarsal fusions, and ocular, e.g., microphthalmia and coloboma, phenotypes. To assess the role of GDF6 in the pathogenesis of renal malformation, we performed targeted sequencing in 193 further patients identifying rare GDF6 variants in two cases with kidney hypodysplasia and extrarenal manifestations. During development, gdf6 was expressed in the pronephric tubule of Xenopus laevis, and Gdf6 expression was observed in the ureteric tree of the murine kidney by RNA in situ hybridization. CRISPR/Cas9-derived knockout of Gdf6 attenuated migration of murine IMCD3 cells, an effect rescued by expression of wild-type but not mutant GDF6, indicating affected variant function regarding a fundamental developmental process. Knockdown of gdf6 in Xenopus laevis resulted in impaired pronephros development. Altogether, we identified rare heterozygous GDF6 variants in 1.6% of all renal anomaly patients and 5.4% of renal anomaly patients additionally manifesting skeletal, ocular, or auricular abnormalities, adding renal hypodysplasia and fusion to the phenotype spectrum of GDF6 variant carriers and suggesting an involvement of GDF6 in nephrogenesis.

Left lateral retroperitoneoscopic total nephrectomy of a horseshoe kidney in a 3-year-old boy

The unilateral or bilateral approach for nephrectomy in horseshoe kidney by minimally invasive surgery has been described. A total binephrectomy by a unilateral retroperitoneoscopic approach was performed for congenital nephrotic syndrome. A unilateral retroperitoneoscopic approach was planned in a 3-year-old boy (13 kg) with congenital nephrotic syndrome resistant to steroids with massive protein loss. The operative time was 160 min. The postoperative course was uneventful with continued hemodialysis until renal transplant 18 months later. The unilateral retroperitoneal approach allows total nephrectomy to be completed safely in horseshoe kidney for benign disease. The retroperitoneal access preserves the abdominal cavity, should peritoneal dialysis be required.

A Case of Incomplete Removal of Horseshoe Kidney by Laparoscopic Nephrectomy in an Adult Leading to Urinary Leak: An Eye Opener

Horseshoe kidney is a common congenital fusion anomaly of the kidneys. It poses a challenge to surgeon because of its very variable anatomy in terms of location and lie, fusion, pelvicalyceal system, and the renal vessels. Here we describe a case of laparoscopic nephrectomy in a horseshoe kidney complicated by incomplete removal because of not realizing the lower and medial extent of pelvicalyceal system across midline to the contralateral side leading to persistent urine leak. The relevant anatomy and the necessary precautions to prevent such complication have been discussed.

A deadly trap for para-aortic lymph node dissection in patients with horseshoe kidney as a complication: a case report

Horseshoe kidney is a rare congenital renal dysplasia. It is often associated with various anatomical abnormalities, including renal vessel and ureter variability, which increase unpredictable surgical risks. This current report describes the case of a 42-year-old woman diagnosed as having cervical squamous cell carcinoma complicated by horseshoe kidney. She underwent laparoscopic radical hysterectomy, bilateral oophorectomy and lymph node dissection, including dissection of the pelvic, presacral and para-aortic lymph nodes. The surgery was challenging, but no serious complications occurred. Postoperative multi-slice computed tomography angiography confirmed the anatomical variation of the renal location, ureter and renal vessels. To our knowledge, this is the first reported case of cervical carcinoma complicated with horseshoe kidney.

Diameters of Arteries Supplying Horseshoe Kidneys and the Level They Branch off Their Parental Vessels: A CT-Angiographic Study

Background: The most common renal fusion anomaly is horseshoe kidney (HSK), a condition associated with variable arterial blood supply. The aim of this study was to determine whether the height of origin of the renal artery determines its diameter and whether it differs from the mean diameter of the renal arteries of normal kidneys (NK). Methods: Computer tomography angiography (CTA) studies of 336 patients (88 HSK and 248 NK) were obtained in a search of renal arteries; these were than classified into four groups according to height of its origin: Group I, branching from the aorta superior to the inferior mesenteric artery (IMA); Group II, branching from the aorta below the IMA; Group III, branching from the iliac artery; and Group IV, originating from the internal and external iliac artery. Results: The HSK group included 398 arteries (mean diameter 4.30 mm) and the NK group 598 (5.52 mm) (p < 0.0001). In the HSK group, the mean diameters according to groups were: Group I, 4.54 mm; Group II, 4.28 mm; Group III, 3.41 mm; and Group IV, 3.43 mm. Statistically significant differences were found between arteries originating from the aorta and arteries branching from the iliac arteries (p < 0.0001). In the NK group, the corresponding values were: Group I, 5.53 mm; and Group II, 4.45 mm. The number of arteries supplying the HSK wider than 3.0 mm were: Group I, 83.0%; Group II, 82.4%; Group III, 68.4%; and Group IV, 66.6%. Conclusions: The renal arteries of the HSK branch from their parental vessels at lower levels and have smaller diameters than those of NK.

Deployment of a Resuscitative Endovascular Balloon Occlusion of the Aorta Device in a Case of Gunshot Wound Injury to a Horseshoe Kidney

A horseshoe kidney (HSK) is a urological malformation that is typically found incidentally after a traumatic injury due to its asymptomatic nature. We present a 25-year-old male with multiorgan injuries secondary to blunt abdominal trauma caused by a gunshot wound. We report the courses of action taken that led to the identification of the HSK and other associated intra-abdominal injuries and the subsequent surgical management. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an improving minimally invasive technique that was used to control hemorrhage in the early preoperative stages and during surgical repair of the injuries. Multiorgan injuries that involve an HSK are uncommon. Our interest in the case relies on the rarity and unique aspects of the injuries and the recovery of the patient following the use of REBOA.

The level of origin of renal arteries in horseshoe kidney vs. in separated kidneys: CT-based study

Purpose

Horseshoe kidney is a rare congenital anomaly with potential clinical implications. The aim of this study was to determine the number of renal arteries and veins and the level at which the arteries branched off their parental vessels in individuals with horseshoe kidney (HSK) and in persons with separated kidneys (SK).

Materials and methods

The analysis included computed tomography angiography studies of 331 patients (83 HSK and 248 SK). The number of renal vessels and diameters of renal arteries were determined, along with the level at which they branched in relation to other ramifications (four groups of origin were proposed) and their entrance of the vessels to the kidney.

Results

Number of renal arteries in HSK group was 4.57 ± 1.39 per patient and 2.4 ± 0.43 in SK group (p < 0.0001). The distribution of branching level of renal arteries in HSK group was: I group ~ 57%, II group ~ 27%, III group ~ 15% and IV group < 1%, whereas in SK group the distribution was respectively: I group ~ 99%, II group < 1%, III and IV group − 0% (p = 0.0001). In HSK group, diameter of renal arteries branching above the IMA was 4.61 ± 1.58 mm, as compared with 3.96 ± 1.34 mm for the arteries branching below (p = 0.0004). Number of veins was 566 in SK group (87.70% of kidneys were supplied by single vein) and 323 in HSK group (9.64% kidneys were supplied by two veins) (p < 0.0001).

Conclusion

In HSK group, renal arteries significantly more often branch off their parental vessels below the origin of IMA and such vessels are usually smaller.

Horseshoe kidney and associated anomalies: Single institutional review of 20 cases

BACKGROUND

Horseshoe kidney (HSK) is a common renal fusion anomaly. We undertook this study to discuss various anomalies associated with HSKs. The objective of the study is to study various anomalies associated with HSKs and to assess the need for surgical intervention in patients with these anomalies.

PATIENTS AND METHODS

This is a retrospective cohort study of twenty patients who presented to our institute with the diagnosis of HSKs. The data were analysed with regard to age at presentation, symptoms, associated anomalies, investigations and surgical intervention.

RESULTS

Twenty patients were included in this study. They were referred either with a diagnosis of HSK or were diagnosed during investigations for symptoms and during workup for associated anomalies. Eleven patients were incidentally diagnosed and were asymptomatic, and there were no associated anomalies diagnosed in these patients. Nine patients were symptomatic and were diagnosed with various associated anomalies. Our results concur with recent literature review which suggests that nearly half of the patients with HSKs have associated anomalies. In the present series, all symptomatic patients with associated anomalies required surgical intervention.

CONCLUSION

HSKs being a common fusion anomaly, necessitates a prompt and thorough search of the search for any associated anomalies. Many of these anomalies may require surgical intervention.

Role of magnetic resonance urography in pediatric renal fusion anomalies

Renal fusion is on a spectrum of congenital abnormalities that occur due to disruption of the migration process of the embryonic kidneys from the pelvis to the retroperitoneal renal fossae. Clinically, renal fusion anomalies are often found incidentally and associated with increased risk for complications, such as urinary tract obstruction, infection and urolithiasis. These anomalies are most commonly imaged using ultrasound for anatomical definition and less frequently using renal scintigraphy to quantify differential renal function and assess urinary tract drainage. Functional magnetic resonance urography (fMRU) is an advanced imaging technique that combines the excellent soft-tissue contrast of conventional magnetic resonance (MR) images with the quantitative assessment based on contrast medium uptake and excretion kinetics to provide information on renal function and drainage. fMRU has been shown to be clinically useful in evaluating a number of urological conditions. A highly sensitive and radiation-free imaging modality, fMRU can provide detailed morphological and functional information that can facilitate conservative and/or surgical management of children with renal fusion anomalies. This paper reviews the embryological basis of the different types of renal fusion anomalies, their imaging appearances at fMRU, complications associated with fusion anomalies, and the important role of fMRU in diagnosing and managing children with these anomalies.