Surgical and histological boundary of the hepatic hilar plate system: basic study relevant to surgery for hilar cholangiocarcinoma regarding the "true" proximal ductal margin.

Background: We sought to expand the clinico-anatomical limit of the proximal ductal margin (Limit-PDM) for resectability of hilar cholangiocarcinoma (HCCA).

Methods: The practical boundary of the hilar plate (PBHP) was defined as the location where the bile duct (BD) could not be isolated by dissection. The distance between PBHP and two well-known clinical landmarks of Limit-PDM, the right edge of the bifurcation of the anterior and posterior branch of the right portal vein (Posterior-Landmark) and the left edge of the umbilical portion of the portal vein (Left-Landmark), and histological features around the PBHP were assessed using 55 adult cadaver livers.