Intrahepatic cholangiocarcinoma with micrometastasis in the portal tract of the liver.

Intrahepatic metastasis of intrahepatic cholangiocarcinoma (ICC) has not been evaluated in detail. We report a case of mass-forming type ICC with micrometastasis to the distant portal tract in a 40-year-old woman. In 2006, she was given a diagnosis of mass-forming type ICC, 4 cm in diameter, and right hepatectomy with lymph node dissection was performed. Macroscopic findings showed an irregular white mass-forming type lesion with two small daughter lesions and portal vein invasion in the S5 subsegment. Microscopically, other cancer cells within vessels had proliferated in the peripheral portal tract of the S8 subsegment, and these cancer cells in the portal tract had invaded the vessel wall. The endothelial cells of the vessels around the cancer cells were positive for CD34, but negative for D2-40 and CK19 on immunohistochemical analysis. Therefore, intrahepatic metastasis of cancer cells through the portal vein was diagnosed. Intrahepatic metastasis of cancer cells through the portal vein was demonstrated in a patient with mass-forming ICC.