Extrarenal Pyelocalyceal System or Extrarenal Calyces: A Case Series and Literature Review

Abstract

Extrarenal pyelocalyceal system or extrarenal calyces, a congenital anomaly, is identified when it presents with pelviureteric junction obstruction. It is elusive to preoperative diagnosis and was identified only intraoperatively in all published pediatric cases. Experience gained by managing a series of cases and a literature search has guided us to evolve a preoperative diagnostic approach, a pyelotomy technique, and a practical classification of the EPS. During the period from 2003 to 2023, four cases with six kidneys of the EPS including three kidneys of the polar extrarenal infundibulum and calyces, a variant of EPS involving only upper or lower pole of the kidney, were seen. Successful pyeloplasty was performed in five of the six kidneys for PUJO using a careful pyelotomy technique. Characteristic "garden rake" X-ray sign was seen in intravenous urogram or retrograde pyelogram, contrast-enhanced computerized tomogram, or magnetic resonance imaging (MRI) of the abdomen in three kidneys. Retrograde pyelogram, CECT, or MRI of the abdomen identified the polar variant in three kidneys. Late-onset PUJO was seen in one case. Four cases with PUJO presented with significantly reduced renal function. One showed postoperative deterioration to nonfunction despite good drainage. A preoperative diagnostic approach, a pyelotomy technique for pyeloplasty, and a classification of the EPS are evolved by the authors. Progressive loss of function and late-onset obstruction mandate a renal-sparing pyeloplasty approach and follow-up.

Keywords: Anomalies of kidney; extrarenal calyces; extrarenal pyelocalyceal system; pelviureteric junction obstruction; pyeloplasty.

Figure 1

Case 1 – 1A - Antenatal ultrasonogram (USG) showing left hydronephrosis, 1B1 - Early intravenous urogram (IVU) film showing small hand garden rake (SHGR) sign on both sides, 1B2 - Late IVU film showing a large low-placed hydronephrotic pelvis on the left side, 1C1 - Postnatal USG showing left discoid kidney with hydronephrosis, 1C2 - Postnatal USG showing right discoid kidney, 1D - Contrast-enhanced computerized tomogram (CECT) showing CECT bilateral discoid kidneys, SHGR sign on the right side and left hydronephrosis, 1E - Retrograde pyelogram showing left rotated discoid kidney with SHGR sign of EPS and dilated pelvis and right rotated kidney with SHGR sign, and 1F - Intraoperative photo showing EPS on the left side. Case 2 – 2A1 - USG showing left hydronephrosis, 2A2 - USG showing normal right kidney, 2B - Intraoperative photo showing EPS, 2C1 - Postoperative magnetic resonance imaging (MRI) showing anteroposteriorly discoid, low-placed, and rotated kidney with SHGR sign on the operated side and a normal right kidney, 2C2 - MRI showing normal right kidney, 2C3 - MRI showing SHGR sign on the operated left side

Figure 2

Case 3 – 3A1 - Ultrasonogram showing left hydronephrosis, 3A2 - Right hydronephrosis, 3B - Retrograde pyelogram showing bilateral PUJO and distorted pelvicalyceal system and left single prong of small hand garden rake sign, 3C1 and 3C2 - Intraoperative photos showing left kidney with upper polar PEIC, opened dilated pelvis, and pelviureteric junction, 3D1 - Postleft pyeloplasty contrast-enhanced computerized tomogram showing left upper PEIC and right PUJO and upper PEIC, 3D2 - CT Angiogram does not show any vascular anatomical changes

Figure 3

Case 4 – 4A1 - Ultrasonogram (USG) at the age of 2 years showing right normal kidney, 4A2 - USG at the age of 2 years showing left kidney with mild rotational anomaly and anteriorly facing pelvis, 4B1 - USG at 9 years age showing right normal kidney, 4B2 - USG at 9 years showing left hydronephrosis, 4C1 - Left retrograde pyelogram (RGP) showing laterally placed pelviureteric junction (PUJ) and dilated calyces, 4C2 - Left RGP late film showing PUJO, 4D1 - Intraoperative photo showing left upper polar extrarenal infundibulum, dilated pelvis and PUJ, 4D2 - Opened left pelvis showing the opening of the extrarenal infundibulum and 4D3 - Sketch showing the excised part of dilated pelvis with PUJ and residual left pelvis with adequate strip of pelvic wall left behind outside the opening of the upper polar infundibulum and rest of the calyceal openings