Polycystic Horseshoe Kidney Anomaly

Seyed Reza Hosseini, MD; Shahram Gooran, MD; Farshid Alizadeh, MD; Shahrzad Dadgari, MD


Appl Radiol. 2009;38(9) 

Case Summary

A 31-year-old man presented with an incidental finding of microscopic hematuria during a routine check-up. In complementary work-ups, a high serum BUN and creatinine level were also noted, and a renal ultrasound was performed. The ultrasound showed multiple bilateral renal cysts with suspicious bilateral hydronephrosis. Exact evaluation of the hydronephrosis was impossible due to the presence of numerous kidney cysts.

Laboratory findings were:

  • normal CBC,

  • microscopic hematuria (8-10 RBC/HPF)

  • no pyuria,

  • serum BUN = 45

  • creatinine = 2.1

  • other findings were normal.

The physical examination was normal but the patient said that he experienced occasional vague abdominal pains for a few months. He also stated that his mother had undergone renal transplantation about 15 years ago and that 4 of his cousins had renal failure and were under hemodialysis.

We performed bilateral ureteroscopy to rule-out the obstructive nephropathy. The left ureter was normal but there was a moderate stenosis in the right ureter and a double-pigtail ureteral stent was placed. On performing a kidney-ureter-bladder (KUB) radiograph to assess the correct position of the stent, we noted an unusual stent path (Figure 1). We performed an abdominal computed tomography (CT) scan to rule-out mass lesions that could possibly displace the right ureter. We were unable to perform an intravenous pyelogram because of the high creatinine levels. On CT scan, we found that the kidneys were also in a horseshoe formation (Figure 2) and the diagnosis of polycystic horseshoe kidney was confirmed. Since the serum creatinine level remained unchanged, the stent was removed and no hydronephrosis was observed on repeat renal ultrasound (Figure 3).

Figure 1.

KUB shows lateral deviation of the JJ stent.

Figure 2.

CT scan demonstrates polycystic kidneys with fusion of the lower poles.

Figure 3.

Renal ultrasonography reveals multiple cysts in both kidneys as well as isthmus without hydronephrosis.

Imaging Findings

The KUB showed lateral deviation of the JJ stent within the right ureter (Figure 1). CT kidney images showed fusion of the lower poles of the kidneys. The JJ stent was also visible in the right ureter (Figure 2). The ultrasound after stent removal showed multiple cysts in both kidneys as well as the isthmus. A large cyst containing a hematoma was visible in the left kidney (Figure 3).


Polycystic horseshoe kidney anomaly.


About 1 in 1000 individuals has some type of renal fusion, the most common being the horseshoe kidney. The incidence of horseshoe kidney is 1 in 400 to 1 in 800 people, and is more common in boys than girls.[1,2] The two kidneys fuse across the midline,usually at their lower poles, by renal tissue or a fibrous band. The horseshoe kidney is usually lower than normal because the inferior mesenteric artery limits its ascent. It can also be malrotated and is prone to reflux, obstruction, infection and stone formation. The autosomal-dominant form of polycystic kidney disease (ADPKD) is an important cause of renal failure, accounting for 10% to 15% of patients who receive hemodialysis.[4] The incidence of this anomaly ranges from 1 in 500 to 1 in 1000 cases. Because of the presence of multiple cysts, the diagnosis of hydronephrosis on ultrasound may be difficult. It is not uncommon for urologists to be involved in the care of patients with either adult polycystic kidney disease or horseshoe kidney disease. It is rare with incidence ranges of 1 in 134,000 to 1 in 8 million to have these 2 congenital disorders simultaneously in the same patient.[2,3] Less than 20 cases have been reported in the literature.[2,3]


Patients with adult polycystic kidney disease, usually develop renal failure after 40 years of age. Co-occurrence of this disease with horseshoe anomaly may lower the age of renal failure and warrant closer follow-up for younger patients.


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