An Accessory Right Hepatic and Cystic Arteries Derived from the Superior Mesenteric Artery: A Cadaveric Case Report

BACKGROUND The configuration of the hepatic arteries is known to vary substantially between individuals. Here, we report a rare retroperitoneal configuration of an accessory hepatic artery existing alongside a left and right hepatic artery branching from the proper hepatic artery. During routine dissection, we discovered an anomalous configuration of the hepatic arteries that does not fit the commonly used categorizations for abnormal hepatic vasculature. We briefly discuss potential implications of this finding. CASE REPORT The left and right hepatic arteries branch directly from the common hepatic artery and supply the liver. The accessory hepatic artery arises directly from the superior mesenteric artery, travels posterior to the portal triad, and enters the porta hepatis. It was found to travel posterior to the neck of the pancreas, duodenum, and portal triad at the same depth as the inferior vena cava, suggesting that the accessory right hepatic artery was traveling retroperitoneally, posterior to the opening of the lesser sac. The accessory hepatic artery exclusively supplies the cystic arteries. Considering existing classification schemes, our case most closely resembles Michels's type 6 and Hiatt's type 3, but most specifically López-Andújar's type 6. To the best of our knowledge, this is one of the first reported cases of a retroperitoneal accessory right hepatic artery. CONCLUSIONS Knowledge of the possible variations of the hepatic arteries is important to reduce the risk of iatrogenic injury and improve patient outcomes in surgery, especially in laparoscopic cases or pancreatoduodectomies where more unique variants may be especially difficult to identify or easier to injure. Future research should explore the frequency of retroperitoneal accessory right hepatic arteries, as their unique course may be easily missed.