Influence of Anatomical Variations due to Horseshoe Kidney on Colorectal Cancer Surgery.

BackgroundHorseshoe kidney is a rare renal fusion anomaly often associated with vascular and ureteral variations. Previous case reports have described technical considerations during colectomy in patients with horseshoe kidney. However, studies systematically evaluating the impact of anatomical anomalies associated with horseshoe kidney on surgical procedures remain limited.MethodsWe retrospectively analyzed 13 patients with horseshoe kidney who underwent colectomy for primary colorectal adenocarcinoma at a single center between April 2007 and December 2024. Venous anomalies were primarily evaluated using contrast-enhanced computed tomography. Aberrant renal arteries, ureter course, and renal hilum orientation were also assessed. We further assessed how these anatomical variations influenced the dissection strategy, vascular control, and short-term surgical outcomes.ResultsTumor locations included the left-sided colon (n = 9), right-sided colon (n = 3), and transverse colon (n = 1). Aberrant renal arteries were identified in 69.2% of patients and aberrant renal veins in 84.6%. Notably, 38.5% of patients had aberrant renal veins coursing near the inferior mesenteric artery, requiring particular caution during the medial approach. In left-sided colectomy, anterior displacement of the mesocolon and retroperitoneal structures may increase the risk of unexpected vascular or retroperitoneal injury. However, all aberrant vessels were detected on preoperative CT. No postoperative complications exceeded Clavien-Dindo Grade III.DiscussionIn colorectal cancer patients with a horseshoe kidney, surgeons should expect anterior displacement of retroperitoneal structures and carefully evaluate aberrant renal veins near the inferior mesenteric artery. Systematic preoperative imaging assessment is essential for safe medial dissection for left-sided colectomy and prevention of vascular injury.