[Three deceptive cases of intrahepatic metastases of colorectal origin with endobiliary growth, simulating cholangiocarcinoma. Importance of immunostaining of cytokeratin 7 and 20].

Malignant tumors of the liver with intrabiliary growth are rare, except for some cholangiocarcinomas. Metastases with intrabiliary growth, whatever their origin, are rare. Moreover, colorectal metastasis can be particularly difficult to distinguish morphologically from some cholangiocarcinomas. We report 3 cases of late colorectal metastasis with intrabiliary growth, presenting as cholangiocarcinomas of the large ducts. Immunostaining with cytokeratins 7 and 20 attested the diagnostic and pointed out the spreading pattern of colorectal metastasis within biliary ducts. This study illustrates the capacity, probably underestimated, for colorectal metastasis to develop in the lumen of bile ducts and emphasizes the relevance of cytokeratin 7 and 20 immunostainings in such cases.