Retroperitoneoscopic surgical resection of a crossed ectopic non-functioning multicystic kidney associated with a severe ureteral dilation. A new surgical approach and literature review

Abstract

After horseshoe kidney, crossed renal ectopia (CRE) is the most common fusion anomaly of the kidney, with an incidence of 1:7000 autopsies. Most frequently the left kidney is the crossed ectopic component. In this article we present the first case of retroperitoneoscopic resection of a CRE and left ectopic multicystic dysplastic kidney with severely dilated ureter.

1 Introduction

After horseshoe kidney, crossed renal ectopia is the most common fusion anomaly of the kidney, with an incidence of 1:7000 autopsies. The fused variant it is 8 times more frequent than the non-fused variant. The true incidence of CRE is not known as it is predominantly a silent entity and in older adults, the fusion anomaly is usually discovered by coincidence. Most frequently, the left kidney is the crossed ectopic component.

The vascularization of a cross kidney is always aberrant. The vascular supply can be provided by vessels generally arising from the lower aorta (near the bifurcation), the common iliac artery or the left external and internal iliac arteries. Due to numerous vascularization variants, radiological imaging is fundamental for studying the anatomical relationships with neighboring organs and vessels of a crossed ectopic kidney, allowing for the best surgical approach.

In a series of 36 patients most children with CRE presented within one year of age, with urinary tract infection being the most common presenting symptom. The most frequently associated anomaly was anorectal malformation.

We present a case of left-to-right crossed and fused multicystic dysplastic ectopic kidney associated with left hydronephrosis and a severe left ureteral cyst. Our patient underwent a surgical resection of the left kidney and the dilated ureter via a retroperitoneal approach combined with cystoscopy and placement of a temporary JJ stent in the normal right ureter. This is the first case of laparoscopic retroperitoneal approach in a crossed ectopic and multicystic kidney described in the literature making this case report useful and interesting for the scientific community since the previously reported cases were not presenting with the same clinical features and were treated by laparotomy.

2 Case report

A one-month-old child was referred to our hospital due to left a ectopic dysplastic kidney located beneath the inferior aspect of the right kidney, associated with a dilated left ureter and normal appearance of the bladder. He also presented with an undescended testis on the left side. The diagnosis was initially made by a routine antenatal ultrasound which also showed left cystic structure in the bladder described as a ureterocele and was confirmed by magnetic resonance imaging (MRI). Since the newborn period prophylactic antibiotics were started. A voiding cystourethrogram showed opacification of a short ureteral stump on the left. The bladder and the urethra had a normal appearance. No reflux was observed in the right kidney.

A hippuran dynamic renal scintigraphy showed a non-functioning left kidney and a right kidney with homogeneous parenchyma, compensatory function, and normal voiding capacity at one month of age. At the same age, blood tests revealed normal cystatin C levels at 1.65 mg/L, which was within the reference range. Creatinine was also normal at 25 μmol/L, and the electrolyte balance was within normal limits.

We initially opted for an observational approach, and the patient underwent serial ultrasonographic (USG) examinations twice per year during his first years of life, hoping for an involution of the dilated structures in the crossed left-to-right ectopic kidney. Routine visits to our outpatient clinic were scheduled to discuss the ultrasonographic results with the family and to ensure there were no breakthrough urinary tract infections. At almost one year of age, the left testis was still undescended, and surgical fixation was planned for 18 months of age. The left orchidopexy was performed through inguinal and scrotal incisions without complications in an ambulatory day hospital setting. During the operation, an absence of the left vas deferens was observed. This finding can be associated with alterations in the development of the mesonephric structures and the ureteric bud.

When the patient was almost three years old, the ultrasonographic report showed a worsening of the dilation in the left ureter, measuring 10 x 5 × 6 cm. Moreover, the ultrasound revealed the presence of sediment in the lowest part of the dilated structure. The right kidney was well-differentiated and vascularized, with dimensions of 88 × 36 mm ( Fig. 1 ).