A case of horseshoe kidney with surplus renal arteries.

During a gross anatomy course at Kurume University School of Medicine in 2001, an anomaly of the kidneys was found. The lower ends of the kidneys were fused by a renal substance and formed a horseshoe kidney located ventral to the abdominal aorta and inferior vena cava. Both renal hila opened very widely in the ventral direction, with the left hilum being larger than the right. This horseshoe kidney had original left and right renal arteries that branched from the abdominal aorta. As well, there were four surplus renal arteries. The first surplus artery branched from the right renal artery and was distributed to the upper pole of the right kidney. The second arose from the abdominal aorta and was distributed to the inferior pole of the right kidney. The third arose from the abdominal aorta and was distributed to the inferior pole of the left kidney and part of the isthmus. The fourth branched from the abdominal aorta and was distributed to the upper pole of the left kidney. The incidence of horseshoe kidneys in Japanese anatomical dissections has been reported as 0.15-0.48%. This was the sixth such case for our laboratory, representing a frequency of 0.1% (6 of 1902 dissections) from 1952 to 2001.