Incidence and Spectrum of Renal Complications and Extrarenal Diseases and Syndromes in 380 Children and Young Adults With Horseshoe Kidney.

OBJECTIVE: The objective of our study was to evaluate the incidence and spectrum of renal complications and of extrarenal diseases and syndromes in children with horseshoe kidney (HSK).

MATERIALS AND METHODS: The clinical data and imaging studies of 380 subjects (median age, 2.8 years) diagnosed with HSK over a 24-year period were reviewed: 366 children and young adults and 14 fetuses, one of whom died in utero. All renal complications and extrarenal diseases and syndromes were documented. Patient age, initial imaging modality, follow-up imaging modalities, and imaging modality at diagnosis were recorded.

RESULTS: One hundred seventy-five patients (46.1%) had renal complications. Pelvocaliectasis without an identifiable cause was the most common complication (n = 83, 21.8%) followed by vesicoureteral reflux (n = 37, 9.7%). Less common renal complications included duplex kidney, multicystic dysplastic kidney, renal stones, asymmetric renal size, ureteropelvic junction obstruction, ureteral stones, acute pyelonephritis, trauma, and renal rhabdomyosarcoma. One hundred ninety patients (50%) had extrarenal diseases or syndromes. Gastrointestinal tract (n = 62) and vertebral (n = 54) anomalies were the most common. Forty-nine patients had syndromes. Turner syndrome was the most common (n = 16) followed by caudal regression syndrome (n = 9). HSK was missed on initial imaging in 42 of 364 postnatal renal examinations and was diagnosed later. The patient groups with renal complications and with extrarenal diseases or syndromes and a missed diagnosis of HSK were significantly younger than the groups without them (p < 0.05, Wilcoxon rank sum test).

CONCLUSION: Half of children with HSK have renal complications or extrarenal diseases or syndromes. The incidence is higher in younger children, and the spectrum of complications, diseases, and syndromes differs from those reported in previous studies of adults with HSK. Children with HSK, especially young children, therefore require follow-up renal examinations and extensive extrarenal workup.