Quiz Page March 2007
Article Outline
Clinical Presentation
A 6-year-old boy had an episode of painless gross hematuria. There was no recent history of infection or skin rash. Family history is significant for kidney stones on the father’s side. He was initially seen by his primary care physician and a urine dipstick showed a large amount of blood and more than 0.3 g/dL (3 g/L) of protein. Microscopy showed red blood cells too numerous to count. No cast or dysmorphic red blood cells were found. Random urine for calcium to creatinine ratio was 0.3. Intravenous pyelogram (Fig 1) was performed.
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Figure 1.
Intravenous pyelogram of a 6-year-old boy presenting with painless gross hematuria.
■What is your diagnosis?
Discussion
What is your Diagnosis?
The intravenous pyelogram shows left side duplex collecting systems. There is a stone of 1 cm diameter on the right side (Figure 2, Figure 3). The axes of both sides of the kidney are rotated. The upper and lower calyces on the left side are projected medially and anteriorly, respectively. The calyx on the right side is elongated in shape and is opening anteriorly (Fig 4). There is no hydronephrosis or ureteral obstruction observed in the intravenous pyelogram. Both the ureters are normal in caliber. Ultrasound (Fig 5) was done after the patient was seen and it shows a large horseshoe kidney with lower poles connected anterior to the aorta.
Figure 2.
Intravenous pyelogram shows left side duplex collecting system. A stone is seen on the right side (arrow).
Figure 3.
KUB (kidney, ureter, bladder) of the same patient before the injection of contrast medium. A stone of 1 cm size is seen on the right kidney.
Figure 4.
Intravenous pyelogram shows that the calyceal system opens anteriorly on the right side.
Figure 5.
Ultrasound showing a horseshoe kidney with parenchyma crossing the midline over the aorta.
A horseshoe kidney consists of two functioning kidneys on each side of the midline. The kidneys are connected at the lower poles by either an isthmus of functioning parenchyma or fibrous tissues. The collecting systems are often rotated anteriorly. The incidence of horseshoe kidney is about 1 case in 400 to 600 persons worldwide.1 Although 90% of pediatric patients with horseshoe kidney are asymptomatic, they are more prone to have kidney stones, hydronephrosis, hematuria, and infection.2 The patient in this vignette also has positive family history of stones and hypercalciuria. The proteinuria is probably secondary to blood contamination in concentrated urine. Subsequent urinalysis showed negative protein.
Final Diagnosis
Horseshoe kidney with a double calyces on the left side and a stone on the right side.
References
Case Provided By Keith K. Lau, MD, Lavjay Butani, MD, and Maha N. Haddad, MD, Department of Pediatrics, University of California, Davis
Support: None.
Potential conflicts of interest: None.
PII: S0272-6386(06)01700-8
doi:10.1053/j.ajkd.2006.11.029
