Extrarenal calyces associated with pelviureteric junction obstruction: A case report of a rare anomaly.

Extrarenal calyces are one of the rare renal anomalies associated with the collecting system. Their association with renal ectopia or horse shoe kidney is known. But, here in, we are reporting an intraoperative surprise, where extrarenal calyces were associated with pelviureteric junction obstruction and routine preoperative imaging did not show any light on the diagnosis.

INTRODUCTION

Extrarenal calyces are rare anomalies of the upper urinary tract. Only 20 cases were reported so far in the literature. The rarity of this anomaly and the complexity of possible associated anomalies often makes the preoperative diagnosis difficult. They are known to be associated with other anomalies, including bifid kidney and renal dysplasia.[1] To the best of our knowledge, only 3 cases have been reported in the literature wherein, it was associated with pelviureteric junction obstruction (PUJO).[2-4] When associated, management options depend on the renal function and presenting symptoms. Herein, we are reporting a case where routine preoperative imaging did not throw any light on the diagnosis and was an intraoperative surprise. The surgical perspectives have been highlighted. Knowledge of this rare anomaly helps to prevent inadvertent injury to the pelvicaliceal system.[5]

CASE REPORT

A 9-year-old male child presented to us with complaints of pain in the left flank for 1 month. The pain was dull aching and intermittent in nature. There was no other significant history. The clinical examination of the child was essentially normal. An ultrasound of the abdomen showed severe hydronephrosis of the left kidney with a parenchymal thickness of 2 mm with upper ureteric dilation. The right kidney was normal. A radionuclide scan showed a poorly functioning left kidney with a split renal function of 7% with obstructed curves. An ante grade dye study was done, which showed significant stasis in the hydronephrotic kidney and the ureter was not visualized.

The patient was taken up for pyeloplasty with a working diagnosis of classic PUJO. Intraoperatively, a large dilated kidney with papery thin cortex was found with 5 pseudopodia-like projections (extrarenal calyces) arising from it and connected to the pelvis; PUJO was noted. The rest of the ureter appeared normal. In view of the complex nature of the lesion and poorly functioning kidney, a right nephroureterectomy was performed [Figure 1].

Figure 1

Excised specimen

DISCUSSION

The presence of extrarenal calyces is a very rare anomaly of the upper urinary tract that was first described in 1925.[6] A few cases were reported in the literature and the exact etiology of this condition is unclear.[2] It has been hypothesized that the anomaly could be due to a disparity resulting from slow development of the metanephric tissue or to a relatively rapid development of the ureteric bud.[2] A kidney with extrarenal calyces is usually associated with other anomalies, such as bifid kidney, renal ectopia, horseshoe kidney, and renal dysplasia.[1] The presentation of these anomalies is variable. It might be an incidental finding diagnosed at autopsy or may present with complications, such as hydronephrosis secondary to associated PUJO, as in our case. Because the incidence of this anomaly is quite low and the clinical presentation is very similar to classic PUJO, a high degree of suspicion should be kept, especially when preoperative radiologic findings are not classical and show distorted calyceal appearance on preoperative imaging studies. This would safeguard against inadvertent injury of the calyces when operating on a well-functioning kidney.[5]

Extrarenal calyces that are present without any complications may require no specific treatment. But, when they are associated with complications, such as PUJO, as in our case, the management is not standardized. Wadhwa et al.[4] (2006) mentioned the successful management of PUJO associated with extrarenal calyces in a pelvic kidney using transperitoneal laparoscopic reconstruction. The management options may include the following: (1) to do a classic pyeloplasty and follow the patient, risking failure of pyeloplasty and recurrent urinary tract infection (UTI) (as was done in the previous case); (2) to resect the pelvis and do a ureterocalicostomy with fusion of the calyces (again associated with extensive dissection and suturing); or (3) to go ahead with a single-stage nephroureterectomy, thereby preventing the child from further recurrent UTI. The management strategies are controversial and should be decided on individual merits and surgeon competence. However, in kidneys with well-preserved function, a renal sparing procedure is worth attempting.