Histological classification of microvascular invasion to predict prognosis in intrahepatic cholangiocarcinoma

Similar to hepatocellular carcinoma, microvascular invasion (MVI) is also one of the most significant prognostic factors of intrahepatic cholangiocarcinoma (ICC). However, there has not been any literature that had mentioned the histologic classification of microvascular invasion in intrahepatic cholangiocarcinoma. We evaluated the significance of MVI classification in this study and analyzed the prognosis based on MVI classification. We herein enrolled 108 patients who were diagnosed with ICC and then underwent surgical exploration from February 2005 to August 2015 at our hospital. We examined them with microvascular invasion (n=43) for four features: the number of invaded microvascular, the maximum number of invading carcinoma cells, the farthest distance from the tumor, and vessel with muscular wall. Thus, Patients were classified into low MVI and High MVI groups according to them. Of the total 108 patients, 65 patients told no detectable MVI, whereas 30 (27.8%) had low MVI, and 13 (12.0%) had high MVI. The median follow-up period lasted 15 months. In the analysis of overall survival, high MVI group showed significantly less positive outcomes than the patients without MVI and the low MVI group, and so did the low MVI group and the patients without MVI. Furthermore, high MVI and low MVI were independent factors for overall survival in ICC patients. We put forward a novel histologic evaluation of ICC which can preferably predict the risk of survival of patients with MVI after curative resection.