Year : 2009 | Volume
: 52 | Issue : 3 | Page : 368--369
Extrarenal calyces: A rare anomaly of the renal collecting system
G Nataraju, BN Nandeesh, MN Gayathri
Department of Pathology, Mysore Medical College and Research Institute, India
B N Nandeesh
#1618, P and T block, Anikethana road 1st cross, Kuvempunagar, Mysore - 570 023
The abnormalities of the renal collecting system represent a complex and often confusing subset of urological anomalies. They manifest in many ways and often make preoperative diagnosis difficult. Extrarenal calyces (wherein the calyces and renal pelvis lie outside the renal parenchyma) is one of the rare anomaly of the collecting system. This anomaly may be associated with other anomalies of the urogenital system. We describe in this case report an unusual case of extrarenal calyces with five long calyces draining a hydronephrotic kidney with associated ureteral atresia. Radiological investigations failed to clearly define these abnormalities. The present case helps in understanding the characteristics of a rare, complex anomaly of the urinary system.
|How to cite this article:|
Nataraju G, Nandeesh B N, Gayathri M N. Extrarenal calyces: A rare anomaly of the renal collecting system.Indian J Pathol Microbiol 2009;52:368-369
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Nataraju G, Nandeesh B N, Gayathri M N. Extrarenal calyces: A rare anomaly of the renal collecting system. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 Jul 6 ];52:368-369
Available from: http://www.ijpmonline.org/text.asp?2009/52/3/368/54996
The urogenital system for some reason is more likely than any other to have birth defects. Their anomalies occur in many varieties and manifestations. Approximately 30% of the children born with congenital anomalies tend to have urogenital abnormalities.  The abnormalities of the collecting system which drains the urine from the kidney represent a complex and often confusing subset of urological anomalies. Extrarenal calyces, which are characterized by calyces and renal pelvis that lie outside the renal parenchyma, is one of the rare anomalies of the collecting system. The rarity of this anomaly and the complexity of possible associated anomalies often make the preoperative diagnosis difficult. We describe a case of extrarenal calyces occurring in a 12-year-old boy.
A 12-year-old boy presented to the surgical department with a left-sided vague, dull abdominal pain associated with a sense of dragging. The past and family history was not significant. On examination, child was afebrile, moderately built and nourished. Pulse rate was 100/ min, regular normal volume; blood pressure and respiratory rate were normal. There was no evidence of lymphadenopathy, icterus or anemia. The respiratory, cardiovascular and the central nervous systems were normal. Abdominal examination revealed an ill-defined, soft, non-tender mass in the left loin region. Biochemical and hematological parameters were within normal limits. The routine urine examination did not reveal any positive findings.
Abdominal ultrasound suggested gross hydronephrosis. Excretory urography did not add much in the evaluation and suggested a non-functioning left kidney. Left nephrectomy was performed and sent for histopathological examination. The gross examination of the specimen received showed a kidney compressed anteroposteriorly by a cystic structure measuring 8 ´ 4 ´ 3 cm. The kidney was enlarged, hydronephrotic with a thin cortex (0.4 cm) [Figure 1]. The kidney communicated with the cystiform structure through five tubular structures, which on an average measured 3.5 cm in length [Figure 2]. The lumen of the tubular structures narrowed as they approached the cystiform swelling which ended blindly without further communication. No ureter was found draining into the bladder (suggesting ureteral atresia). Histopathological examination revealed that the tubular structures draining the kidney and the cystic structure were lined by transitional epithelium with a fibromuscular wall infiltrated by a few mononuclear inflammatory cells. Histology of the kidney showed evidence of atrophy with fibrosis and focal interstitial inflammation.
Of all children born with congenital anomalies, 30-40% have urogenital abnormalities.  Among developmental abnormalities of the upper urinary tract, collecting system abnormalities form an important subset.
The presence of extrarenal calyces is a very rare anomaly of the upper urinary tract that was first described in 1925 by Eisendrath DN  and the total number of cases reported so far is only 20.  The calyces in the present case were long and extrarenal in position. They drained into a cystic structure which represented either a grossly dilated pelvis (pelviureteric junction) or a ureteral cyst. There was no further communication with the bladder and no ureter was found draining into the bladder which suggests ureteral atresia. The exact cause of extrarenal calyces is not very clear, but 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. If the ureteric bud has a rapid or a precocious development, the calyceal system could well develop prior to its coalescence with the nephrogenic mass. Conversely, lag in the growth of the nephrogenic mass could delay its attachment to the collecting system, permitting extrarenal development of the first or second order of the collecting system. , Ureteric atresia results from a failure of canalization of a segment of ureter because of ischemic damage to that portion during the process of elongation of the ureteral bud.  Many cases of collecting system anomalies including extrarenal calyces are detected incidentally or may be diagnosed because of its complications. Cases can go unnoticed to a very late stage, as in the present case. The present case had hydronephrosis, which is often seen as a complication occurring with extrarenal calyces. , Kidney with extrarenal calyces is usually associated with other anomalies like bifid kidney, renal ectopia, horseshoe kidney and renal dysplasia. , However, ureteral atresia with extrarenal calyces is a very rare association and to the best of our knowledge such an association has not been described earlier. Diagnosis of these anomalies requires detailed imaging. Plain radiography is usually not contributory and ultrasonography offers some information which is usually nonspecific. Computerized tomography scan can also be used. Excretory urography often provides good anatomic information. Excretory urography, however, will not be of much help when renal function is poor. The calyces being unsupported are easily distended on retrograde pyelography, thus creating a false impression of hydronephrosis or chronic pyelonephritis. Despite the rare incidence of extrarenal calyces, it is important to bear this anomaly in mind when operating on a kidney which shows distorted calyceal appearance on preoperative imaging studies. This would safeguard against inadvertent injury of the calyces when operating on a well-functioning kidney.  In conclusion, the present case report is a unique one in which extrarenal calyces drain a hydronephrotic kidney with associated ureteral atresia. These features were missed on preoperative radiological imaging studies and thus the present report contributes in understanding the characteristics of a rare, complex anomaly of the urinary system which often makes preoperative diagnosis difficult.
The authors would like to acknowledge the faculty and postgraduate students of the department of Pathology for technical assistance.
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