Intrahepatic Biliary Metastasis of Colonic Adenocarcinoma: A Case Report With Immunohistochemical Analysis.

Although intrabiliary metastasis of carcinoma in the liver is unusual, intraductal and/or intraepithelial spread of cancer cells along intrahepatic bile ducts is now well recognized as hepatic metastasis. However, several clinical and laboratory findings, including images, lead us to differentially diagnose from primary intrahepatic cholangiocarcinoma. We report here on a case of colonic adenocarcinoma that metastasized to the liver with spread along with the intrahepatic bile duct of S5/6 area. The patient was a 51-year-old man and clinically diagnosed liver metastasis of sigmoid colon cancer (tub2, pMP, ly1, v0, n0), which was diagnosed and treated by sigmoidectomy 7 years ago. The right hepatic lobectomy was performed in March 2016 and histopathological examination revealed that moderately differentiated adenocarcinoma proliferated along the epithelium of intrahepatic bile ducts. Immunohistochemistry (IHC) showed that cancer cells in the intrahepatic bile ducts were positive for CK20, CDX2, CK17 and CK19, but negative for CK7, MUC-5AC, MUC-2 and CA19-9. The findings were almost the same as those of the sigmoid colon cancer removed in July 2009. We finally diagnosed the liver tumor as intrahepatic biliary metastasis of sigmoid colon cancer. Patients with liver metastasis of cancer are hard to be detected biliary invasion and spread on diagnostic image examination. Knowledge of distinctive morphological and IHC features can help to accurately diagnose this rare intrahepatic biliary metastasis of colonic cancer in routine pathological diagnostic procedures.