Direct lymphatic spreading route into the liver from the gallbladder: an animal experiment using pig.

In the special occasion that the physiological lymphatic flow is obstructed, gallbladder carcinoma (GBC) may spread into the liver via lymphatic route. Therefore, this study was conducted to find out the direct lymphatic route draining into the liver from the gallbladder using pigs with ligated cystic ducts. After injecting the carbon particle suspension (CH40) or the contrast medium (Lipiodol) into the subserosal layer of the gallbladder, the lymphatic route into the liver was examined both macroscopically and histologically. In controls, CH40 or Lipiodol drained along the cystic duct toward the hepatoduodenal ligament. After occlusion of cystic duct, CH40 was interrupted at the ligated point, and then spread into the liver nearby the gallbladder bed, running off to the liver hilus, toward the hepatoduodenal ligament. This route was confirmed by the Lipiodol drainage into the right median lobe of the liver, equivalent to the segments V and IV a in humans. We presented for the first time the emergence of lymphatic drainage from the gallbladder into the liver after the occlusion of physiological lymphatic route using pigs. This implies that the direct spread into the segments V and IV a of liver should be considered in the surgical treatment of advanced GBC.