CEA and CA19-9 levels in the cystic fluid were elevated not only in patients with biliary cystadenoma and cystadenocarcinoma[18,19] but also in patients with simple hepatic cysts[20,21]; therefore, tumor marker levels in serum and cystic fluid are not useful for distinguishing between a hemorrhagic hepatic cyst and cyst-forming IPNB. Here, CEACAM5 is linked to cystadenocarcinoma.