Supplementary Material for: Laparoscopic resection of the transverse colon cancer with an anomaly of the middle colic artery originating from the splenic artery: A case report.

Introduction: We encountered a colon cancer case with a very rare anomaly of the middle colic artery (MCA) originating from the splenic artery (SA).
Case presentation: A woman was referred to our hospital for transverse colon cancer. Three-dimensional computed tomography (3D-CT) angiography showed an anomalous MCA originating from the SA, rather than from the superior mesenteric artery (SMA) as is typical. Laparoscopic left hemicolectomy with D3 lymph-node dissection was performed. The lymph nodes around the SMA were dissected from the caudal view, confirming the absence of a typical MCA. An anomalous SA-originating MCA was identified just below the pancreas, where it was clipped and ligated; subsequently, total mesenteric excision was achieved.
Conclusion: As D3 lymph-node dissection for transverse colon cancer is technically difficult, 3D-CT angiography is useful for identifying vascular anomalies preoperatively, thereby avoiding intraoperative injury. This is the first case report of laparoscopic colectomy associated with a SA-originating MCA anomaly.