Preoperatively undiagnosable intrahepatic bile duct dilatation contains early-stage intrahepatic cholangiocarcinoma.

Intrahepatic bile duct dilatation is a clue to indicating the presence of IHCC. Moreover it is still often difficult to find IHCC at an early stage in spite of recent progress in the area of molecular biological markers and imaging modalities. We had three interesting cases in which we were suspicious of the presence of IHCC. Preoperative imaging studies of these three cases showed the dilatation and stenosis of the intrahepatic bile duct without any apparent mass. As IHCC could not be ruled out, a hepatectomy was done for the purpose of both diagnosis and treatment of the patients. Postoperative diagnoses were IHCC in one, hepatolithiasis in another and chronic cholangitis in the third patient. A histological analysis revealed that the tumor of IHCC was not infiltrating the parenchyma of the liver with neither vascular nor lymphatic invasion, which suggested that it was an initial nature of the IHCC. In the case of intrahepatic bile duct dilatation and stenosis, which makes it hard to identify IHCC, surgical resection is crucial to make a definite diagnosis and prescribe the most effective course of treatment.