Solitary crossed ectopia with vesicoureteric junction obstruction: A rare case report.

Solitary crossed renal ectopia (SCRE) is a very rare anomaly of urinary tract. Most cases are diagnosed incidentally. We report a case of SCRE associated with vesicoureteric junction obstruction in a 7-year-old child which has not been reported in the literature till date.

INTRODUCTION

Crossed renal ectopia (RE) is a very rare anomaly with an incidence of 1 in 7500 autopsies or 1 in 14,000 pediatric admissions.[12] Solitary crossed RE (SCRE) occurs due to a combination of unilateral agenesis and RE.[3] It is diagnosed incidentally on routine ultrasound or autopsies. The most common associated urological anomaly is vesicoureteric reflux (VUR).[24] We report a case of SCRE associated with vesicoureteric junction (VUJ) obstruction in a 7-year-old male child.

CASE REPORT

A 7-year-old male child was being evaluated for urinary tract infection. Ultrasonography abdomen revealed hydroureteronephrosis with a solitary left kidney with a nonvisualization of the right kidney. General and systemic examination was normal. There was a history of cleft palate surgery at 2 years of age. Routine urine examination revealed pyuria. Renal functions were normal (serum creatinine: 0.7; urea: 30). There was no associated cardiac or vertebral anomaly.

Voiding cystourethrography (VCU) was performed which did not reveal any reflux. Intravenous urogram (IVU) findings demonstrated that the ureter from the left kidney was inserted into the bladder on the right side after crossing the midline [Figure 1]. Furthermore, ureter and pelvis were grossly dilated. Renal radionuclide 99m-technetium (99mTc) -scan was again suggestive of absent right kidney and ectopic left kidney with VUJ obstruction (delayed drainage of whole ureter and kidney) [Figure 2]. Cystoscopy showed one ureteric orifice on the right side which was normal in caliber and could not be cannulated. Upon exploration, diagnosis of VUJ obstruction was confirmed, and intravesical ureteric reimplantation along with tapering of ureter was done. Postoperative period was uneventful, and patient was discharged on 9th postoperative day.

Figure 1

Intravenous urogram showing solitary right to left ectopia with grossly dilated ureter crossing the midline

Figure 2

Renal radionuclide scan showing crossed ectopia with obstruction to drainage at vesicoureteric junction and proximal dilated ureter and pelvis

DISCUSSION

Renal ectopia describes a kidney that lies outside the renal fossa. Simple RE refers to the kidney that remains in ipsilateral retroperitoneal space. Crossed RE exists when a kidney is located on the opposite side of the midline from where ureters enter the bladder. It can be with fusion, without fusion, solitary or bilateral. SCRE results due to renal agenesis of one side and contralateral displacement of the ureter to the opposite side. The crossed RE is a rare disorder, furthermore the incidence of SCRE is exceedingly low, and till now only 35 cases have been reported in the literature.[35]

Like simple RE, SCRE is also asymptomatic and is diagnosed incidentally. SCRE can be diagnosed by ultrasonography and radionuclide scintigraphy using 99mTc-dimercaptosuccinic acid (DMSA) in most of the asymptomatic cases. Excretory urography and multi-detector three-dimensional computed tomography urography are excellent for delineating RE.[5]

In our case, IVU and renal scan were used to arrive at the final diagnosis. 99mTc-DMSA scintigraphy is useful in the diagnosis of simple RE, renal cortical lesions, and function of cortical mass.[6] A high incidence of associated urological abnormalities has been reported in patients with RE. Hydronephrosis is the most significant finding in RE, and the associated VUR is present in 25-70% of cases.[24] Dilatation of the ectopic renal pelvis due to the ureteropelvic junction obstruction is present in 37% of patients.[7] Other abnormalities associated with RE include abnormalities of spinal growth and genital abnormalities such as anorectal malformation, hypospadias, and sacral agenesis. In our case, SCRE (right to left) was associated with VUJ obstruction which was the cause of hydroureteronephrosis. To our best knowledge, this is the first case report in the world literature although VUJ obstruction with crossed RE has been reported in one case which was bilateral.[8] In this case, the ectopic kidney was poorly functioning, while the contra lateral orthotopic kidney was malrotated, with fetal appearance. The global glomerular filtration rate in our patient was 84 ml/min. IVU clinched the diagnosis in our case. Ectopic kidneys are more disease prone than normal kidney, and they are often hypoplastic or dysplastic.[2] Some authors encourage a VCUG in boys and cystoultrasonography in girls affected by crossed RE for the high risk of associated VUR as postnatal US is a poor predictor of VUR.[9] Crossed renal ectopic kidneys are smaller than simple renal ectopic kidneys and have inherently reduced function.[4] A solitary crossed ectopic renal unit will have further worsening of function if associated with an obstructive or refluxing lesion. Furthermore, it is important to distinguish the VUR from VUJ obstruction as association of VUJ obstruction causes a more rapid deterioration of renal function particularly in a solitary renal unit.

Most patients with SCRE do not require treatment for this condition, but because of associated VUJ obstruction reimplantation was unavoidable in our case. We recommend that the urological evaluation should be sought due to the high proportion of these cases have associated urological anomalies.

CONCLUSION

This case of SCRE is probably the 36th case reported. The association of SCRE with VUJ obstruction is probably the first case we reported. Intravenous urography, magnetic resonance urography, and 99mTc-DMSA are the investigations used for the diagnosis of such unusual cases. SCRE usually requires treatment for associated abnormalities rather than for renal problems. An associated VUJ obstruction once documented should be treated urgently to prevent deterioration of renal function.