E1146. Horseshoe Kidney: Common Associations and Complications in the Pediatric Patient
  1. Rana Gordji; University of Mississippi Medical Center
  2. Michelle Basha; University of Mississippi Medical Center
  3. Michael Steiner; University of Mississippi Medical Center
Horseshoe kidney (HSK) is a relatively common renal fusion anomaly occurring in 1 of 400 live births. In most cases, HSK is asymptomatic and noted incidentally on imaging. However, HSK is prone to the development of genitourinary abnormalities and/or may be associated with complex developmental syndromes.

Educational Goals / Teaching Points
Upon review of this educational exhibit, the reader will be able to: describe the embryologic development of the kidneys; identify the normal radiologic findings of HSK across different imaging modalities; describe commonly seen complications of HSK in pediatric patients; identify associated non-urological findings and syndromes; and list the imaging mimickers of horseshoe kidney.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
HSK is thought to be the result of early fusion of the two renal poles across the midline with halted ascension at the level of the inferior mesenteric artery. Due to this abnormal positioning and rotation, patients with HSK are at an increased risk for genitourinary complications. In the pediatric population, ultrasound is the first-line method for evaluation of the kidneys. However, HSK can be reliably diagnosed on most imaging modalities. The most common complication of HSK in pediatric patients is pelvocaliectasis without an identifiable cause or in association with vesicoureteral reflux. Other complications include ureteropelvic junction obstruction, renal cysts, infection, and urolithiasis. The abnormal positioning of HSK also increases the risk of renal injury after trauma. There is also a known increased risk of developing Wilm’s tumor in patients with HSK. Additionally, there is wide anatomic variation of the arterial supply for the HSK as well as variants for venous drainage and ureters. Numerous case reports in the literature have described extrarenal findings in patients with HSK, including vertebral, neurologic, and cardiovascular anomalies. HSK has been reported in higher incidences in patients with Downs, Edwards, Patau, and Turner syndromes. Some of these syndromes are incompatible with life resulting in death at birth. Other renal fusion anomalies include crossed fused renal ectopia and pancake kidney. These can present similarly on imaging with similar complications including urolithiasis and obstruction but are overall far less common.

Most often HSKy is an incidental finding without need for follow-up or intervention. However, given that HSK is one of the most commonly encountered genitourinary variants, familiarity with the imaging findings is important as is awareness of its potential complications. Long-term complications from HSK can follow the patient into adulthood including renal scarring and development of chronic kidney disease.