A histopathologic study of 102 cases of intrahepatic cholangiocarcinoma: histologic classification and modes of spreading.

In our survey of 102 cases of intrahepatic cholangiocarcinoma, 71 peripheral type cases and 31 hilar type cases were observed, the former being prone to metastasize to remote organs and lymph nodes when compared with the latter. These cases were histologically classified into nine histologic types according to the predominant features and rearranged into three groups (well-differentiated, less-differentiated, and uncommon). Although most of these cases were mucin-producing adenocarcinomas with variable grades of differentiation (92 of 102; 90%), several uncommon types were also encountered (ten of 102; 10%), such as adenosquamous, squamous, mucinous, or anaplastic carcinoma. Remote organ metastases were observed more frequently in the less-differentiated group than in the well-differentiated group. In regard to intrahepatic tumor spreading, expansion via sinusoidal spaces (93%), vascular (52%) or lymphatic (18%) involvement, perineural invasion (16%), replacing growth in the bile duct (12%), and permeation in the portal connective tissue (19%) were observed. The cholangiocarcinomas with the vascular involvement presented a higher tendency of intrahepatic as well as extrahepatic metastasis. For correct diagnosis and treatment of cholangiocarcinoma, it seems to be important to possess some knowledge of these histologic types, including their variations and patterns of intrahepatic spread.