Intrahepatic cholangiocarcinoma (IHCC) is the second most frequent primary malignant tumor of the liver after hepatocellular carcinoma (HCC). IHCCs are considered as primary intrahepatic liver tumors. This differentiates them from malignancies of the biliary confluence (Klatskin tumors) that are classified as extrahepatic tumors, along with malignancies of the gallbladder and of the common bile duct. The definition of IHCC (primary tumor of the intrahepatic bile ducts) implies that it encompasses all malignancies arising from the intrahepatic bile ducts, starting from the second-order branches and up to the Hering ducts. This heterogeneity of origins readily explains that the clinical presentation and management of this tumor are quite heterogeneous, depending on whether the tumor originates from the end-order peripheral branches or from the juxtahilar branches. The former is likely to be more frequent than the latter, at least in part because as bile structures divide, their number increases. However, the proportion of each is still ill-defined because mass-forming-type IHCC may behave as hilar malignancies as a result of their location in the vicinity of the biliary confluence or centrifugal extension along the Glissonian pedicles. Three pathological subtypes have been described: mass-forming tumors, which is the most frequent form, described as tumors with clear borders between malignant and nonmalignant tissues; periductal tumors, described as more infiltrative and extended along peri-bile duct tissues without forming a discrete nodular mass; and intraductal tumors characterized by papillary growth within the lumen. These three subtypes seem to have different proliferative activity and different biological behavior: the mass-forming type develops intrahepatic metastases as a result of localized vascular invasion, whereas the periductal type has an infiltration spread via the Glisson capsule and pedicular lymph node metastases. In addition, frequency of lymph node metastases is higher in mass-forming and periductal types compared with intraductal type1 (Fig. 132-1).
Heterogeneity of the morphological presentation of IHCC. The two extreme situations depending on the origin of the tumor are the mass-forming type that originates from the end division of the intrahepatic bile ducts (A) and the periductal infiltrating type that originates from the proximal segmental or sectional bile ducts and resembles a Klatskin tumor (B). Some mass-forming type IHCCs may, however, behave as hilar tumor either when they develop from small bile ducts but in liver segments adjacent to the biliary confluence (C) or when they extend along the Glissonian pedicles (D).
It has been widely assumed in the past, in particular in surgical series, that IHCCs account for a very small proportion (approximately 10%) of all bile duct malignancies.2 In France, for example, the incidence of IHCC in 11 French registries ranged between 0.5 and 1.3 per 105 for men and 0.2 and 0.9 per 105 for women, whereas the respective incidences of all extrahepatic bile duct malignancies ranged between 0.6–1.3 ...