[Anatomy of the caudate lobe of the liver. New aspects and surgical applications].

The caudate lobe is the only real and constant hepatic lobe of mammals and it requires a better delimitation in a modern conception of human liver segmentation. Owing to its dorsal, central and low anatomical situation, this lobe is connected to many segments of the liver and its inflow and outflow vessels are complex and variable. The authors, who studied 242 human livers, describe the typical pattern of these vessels and their anatomical and numerical variants. By its portal branches the lobe seems to depend upon the left lobe of the liver and its arterial and portal inflow as well as its hepatic vein system are better than these of other segments of the liver; moreover this segment can be compared to a quadrangular pyramid which presents an external part, superficial with easy surgical access, and an internal part, deeper and very difficult to resect. It is possible to remove segment I of the liver without any other hepatic resections but, usually, a partial resection of the lobe is performed or a left lateral segmentectomy is required. In liver cancer, the invasion of the lobe generally means widespread tumor dissemination and its resection is not justified; on the contrary, the caudate lobe should be resected for radical operation in hilar cholangiocarcinoma. The tendency of the caudate lobe to overlap with the other 2 liver lobes and its very good inflow and outflow systems explain its ability to avoid postoperative hepatic failure because it can support the hepatic vein drainage and it has a considerable disposition to regenerate.