Table 4 Comparison of four studies on the classification of intrahepatic cholangiocarcinomas
| Â | Aishima, et al. 3 | Liau, et al. 4 | Hayashi, et al. 5 | Present study |
|---|---|---|---|---|
| Â | Japan | Taiwan | Japan | Japan |
Classification criteria | On the basis of the gross appearance. The perihilar type is defined as tumors involving segmental or larger bile ducts, whereas peripheral tumors only affect smaller ducts. | On the basis of microscopic findings. The perihilar type is composed of tall columnar tumor cells arranged in a large glandular pattern, whereas the peripheral type consists of cuboidal to low columnar cells typically arranged in small monotonous glands | According to a scoring system, in which degrees of mucin production and immunohistochemical expression values of S100P and N-cadherin are semiquantitatively evaluated. | On the basis of microscopic findings. Perihilar tumors mainly consist of ductal adenocarcinoma and minor tubular components, if present, restricted to the tumor–liver interface, whereas peripheral cancers have tubular components in the central parts of tumors. |
Incidence of each type | ||||
 Perihilar/peripheral | 44%/56% | 59%/41% | 43%/57%a | 45%/55% |
Gene abnormalities | ||||
 Perihilar/peripheral |  |  |  |  |
 KRAS mutation | NA | 24%/<1% | 29%/2% | 14%/19% |
 IDH1/2 mutation | NA | 5%/17% | 0%/40% | 0%/15% |
 FGFR2 translocation | NA | NA | 0%/11% | NA |
 Loss of BAP1 | NA | NA | NA | 5%/35% |
 Loss of SMAD4 | NA | NA | NA | 33%/4% |
5-year overall survival | ||||
 Perihilar/peripheral | 36%/60% | 21%/37% | 20%/62% | 21%/63% |
