Pelviureteric Junction Obstruction in Ectopic Kidneys with Extrarenal Calyces: A Rare Renal Anomaly.

Extrarenal calyces (ERC) is a rare renal anomaly where calyces lie outside the renal parenchyma and are connected to pelvis by draining infundibulum. Its presentation with pelviureteric junction obstruction presents a confusing intraoperative finding. We report two cases of ERC with pelviureteric junction obstruction in the ectopic kidney. Emphasis is laid on the defining the anatomy so that reader can identify the condition if he comes across similar situation. The two patients were managed by minimal access approach. Management of these cases and review of pediatric cases reported in literature are discussed. Copyright:

INTRODUCTION

Morphological abnormalities of the kidney are varied and range from abnormalities of number, location, and fusion. Extrarenal calyces (ERC) are a rare form of renal anomaly, first described by Eisendrath DN in 1925.[1] The calyces lie outside the renal parenchyma and are connected to the pelvis. They are seen as multiple tubes (3–5 in number) coming out of renal hilum. Since its initial description, <60 cases of ERC have been reported in adult literature both as operative and postmortem findings. The anomaly can be asymptomatic or present with pelviureteric junction obstruction (PUJO), with or without loss of function. Reports in pediatric patients are extremely rare, and presentation in ectopic kidneys is even rarer. We present a report of two cases across two centers who presented with PUJO in ectopic kidneys. They were successfully managed by laparoscopic and robotic approach. Emphasis is laid on defining the anatomy so that reader can identify this condition if he/she comes across a similar situation. Management of these cases and review of pediatric cases reported in literature is discussed.

CASE REPORT

Case report 1

A 2-year-old boy presented with a history of recurrent urinary tract infections and off and on pyuria. The history duration was 9 months. Clinically, he had a vague lump palpable in the suprapubic area more on the left side. His ultrasound showed a normal right kidney with left hydronephrotic ectopic kidney in the left iliac fossa above the bladder. Renal diuretic scan showed 25% function with reduced glomerular filteration rate. Micturating cystouretherogram showed no reflux. The patient was diagnosed to have PUJO in the left ectopic malrotated kidney. He underwent laparoscopic exploration for PUJO. The ports were planned after factoring in the location of the left kidney [Figure 1]. On the initial laparoscopic view, a large lump of the dilated left kidney was seen in the expected location and was displacing the sigmoid loop medially. The renal pelvis was seen near the iliac vessels with abrupt narrowing at PUJ [Figure 2]. Once the renal pelvis was mobilized and lifted up, unusual anatomy was observed at the hilum. The pelvis seemed to be disjointed from the renal hilum and was connected with the kidney via three dilated tubular infundibula. The entire hilum of the left kidney was facing laterally. The anatomy seen in this kidney is schematically represented in Figure 3 with intra operative view. Renal parenchyma appeared normal, and proper visualization of renal hilar vessels could not be done due to unusual anatomy. The PUJO was very distinct, and hence, a small incision was made in the lower abdominal wall to deliver the PUJ and extracorporeal repair was done with a Double J stent across the anastomosis. The patient recovered well, and a follow-up renal diuretic scan showed unobstructed drainage and relief of symptoms. The patient now has a 2-year follow-up and is without any symptoms.

Figure 1

Port position for handling the ectopically located kidney. C – camera port 1 and 2 are working ports

Figure 2

Laparoscopic view of left ectopic kidney with the three calyces. Inset pic shows pelviureteric junction obstruction

Figure 3

Diagrammatic representation of extrarenal calyces with pelviureteric junction obstruction in ectopic malrotated kidney

Case report 2

This case is a 15-year-old girl with right lower quadrant pain associated with nausea and vomiting. She was otherwise healthy with no medical or surgical history. On clinical examination, the abdomen was nontender and there was no palpable lump. On ultrasound, there was a right pelvic kidney with hydronephrosis. She underwent a computed tomography with magnetic resonance urogram (MRU) both showing severe hydronephrosis with malrotated and right ectopic kidney [Figure 4]. Renal diuretic scan showed no excretion and 26% function. The left kidney was normal in location and function. She underwent a retrograde ureterogram which confirmed the MRU findings. She was taken up for robotic exploration. Intraoperatively, the renal pelvis was behind the cecum which was mobilized and after full exposure, there was dilated pelvis connected with the kidney with three dilated infundibular connections. The pelvis and the infundibulum were completely extrarenal and were facing medially. The ureter was on the posterior aspect of the kidney and pelvis. The pelvis was opened, and complete dismembering was not done to avoid retraction of short-length ureter. A Y–V pyeloplasty was done to repair the obstructed PUJ with a Double J stent across the anastomosis. The patient did well and her follow-up scans showed unobstructed drainage with relief of symptoms.

Figure 4

Magnetic resonance urography findings in the second case. Note the ectopic location and the external calyces

DISCUSSION

Abnormal renal anatomy in ectopic kidneys can be very confusing. PUJO can be present in 22%–37% of ectopic kidneys. The ectopia is usually associated with malrotated unit with possible vascular aberrations. These anatomical aberrations can be managed successfully if the surgeon can define the anatomy. PUJO with ERC is a confusing situation which is difficult to predict preoperatively and only reported as intra-operative surprise or analyzed in retrospect. We would like to define the anatomy here. The draining structures of the kidney, i.e., the calyces and its infundibulum end in the pelvis and are completely lying outside the renal parenchyma. There is hilar dissociation between the major calyx and pelvis but connected with each other via infundibulum. Further to this, if there is PUJO, the pelvis becomes dilated with abrupt narrowing distally and proximally, it is connected with multiple tubes (3–5 in number) to the renal hilum. The entire draining anatomy of the kidney seems to have shifted outside the kidney. The schematic representation is given in Figure 3 for clear understanding. This may or may not be associated with additional vascular aberrations.[2]

Treatment of this condition is based on the merit of functional status of the affected kidney. For kidneys with preserved renal function, the treatment mainly lies in relieving PUJO by pyeloplasty. Pelvis reduction or resection is not required. One has to keep in mind the possibility of ligating the calyx while doing reduction pyeloplasty, this may result in hydrocalyx. Wahyudi et al.[3] had reported surgical treatment by resection of the dilated pelvis and side-to-side anastomosis of the calyces and joining the ureter back to the unified calyces. This is quite extensive and may not be recommended in all patients. In the presented two cases, the patients were managed endoscopically (one by robotic and one by laparoscopy). The anatomy was recognized intraoperatively and PUJ was repaired. The outcome in both the patients was successful and drainage was restored with preservation of renal function. Majority of the pediatric reported cases have been treated with nephrectomy because of severely impaired renal function.[4]

Preoperative diagnosis is difficult, especially in ectopic and nonfunctional kidneys. Cadaveric studies defining the patterns of renal calyx anatomy have described this as an anatomical variant.[5] A review of pediatric English literature showed only 11 such similar cases. It can be noted that only three such similar pediatric cases were reported in ectopic kidney. The remaining eight cases were normally located hydronephrotic kidneys with a preponderance to the left side.

Embryological explanations for ERC with PUJO are mostly postulations. The most commonly proposed theory is that it results from a disparity in the growth rate of metanephric tissue which gives rise to renal parenchyma and the ureteric bud which gives rise to the draining system of the kidney.[6] The slow development of the renal tissue delays the attachment to the collecting system, resulting in the formation of the first- and second-order calyceal systems outside the renal tissue.

To conclude, ERC with PUJO is a rare condition and the surgeon should be aware of this anatomical variant. While dealing with ectopic malrotated and dysfunctional kidneys, the abnormal anatomy should always be defined, and PUJO is to be dealt on its own merit. Pyeloplasty is successful and long-term outcome is dependent on the functional status of the kidney.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.