Intrahepatic peripheral cholangiocarcinoma: mode of spread and choice of surgical treatment.

BACKGROUND: Classification of macroscopic appearance and standard operative procedures for intrahepatic cholangiocarcinoma (ICC) are still controversial.
METHODS: The mode of spread of 12 resected ICCs was examined by light microscopy, and the appropriate operative procedures for the various tumours were considered.
RESULTS: Macroscopically, nine tumours were classified as mass-forming type and three as periductal infiltrating type. All patients were treated by major hepatectomy; resection of the extrahepatic bile duct was included in two cases of the periductal infiltrating type. Microscopically, invasion into the portal vein, intrahepatic metastasis and perineural or lymphatic vessel invasion occurred in none, one and all of three tumours of the periductal infiltrating type and in eight, six and six of nine tumours of the mass-forming type.
CONCLUSION: ICC of the periductal infiltrating type has a tendency to spread along Glisson's sheath via lymphatic vessels. By contrast, ICC of the mass-forming type tends to invade the liver via the portal vein system; such tumours begin to invade Glisson's sheath through the lymphatic vessels when the tumour has increased in size. Therefore, major hepatectomy with combined resection of the extrahepatic bile duct should be performed for all ICCs of the periductal infiltrating type and for those of the mass-forming type with invasion of Glisson's sheath.