Clinical significance of anatomical variant of the left hepatic artery for perihilar cholangiocarcinoma applied to right-sided hepatectomy.

Background: Full understanding of the hilar anatomy is crucial for successful surgical resection of perihilar cholangiocarcinoma (PHC).

Methods: The three-dimensional positional relationship between the left hepatic artery (LHA) and the umbilical portion of the left portal vein (UP) was evaluated using multidetector-row computed tomography (CT) in 58 consecutive patients who underwent right-sided hepatectomy for Bismuth-Corlette IIIa or IV tumors. The positional relationship of the LHA related to UP was classified into the following three types: L-UP type, LHA runs into the left lateral section (LLS) from the left caudal side of the UP; R-UP type, LHA runs into the LLS from the right cranial side of the UP; and combined type, one branch of the LHA runs into the LLS from the right cranial side of the UP, and the other from the left caudal side of the UP.

Results: L-UP-type LHA was observed in 53 cases (91.4 %), R-UP type in three cases (5.2 %), and combined type in two cases (3.4 %). No cancer involvement of the LHA was seen in any cases with L-UP type. In one case with R-UP type (one of three; 33.3 %) and one case with combined type (one of two, 50 %), cancer invasion to the LHA was observed at the right side of the UP, requiring combined resection of the involved LHA.

Conclusions: R-UP-type LHA running just along the left hepatic duct may be easily involved by right-side predominant PHC when extending to the left hepatic duct. Hepatobiliary surgeons should recognize this anatomical variant and carefully evaluate the running courses of LHA to successfully perform R0 resection in right-sided hepatectomy for PHC.