Aim: This study aimed to investigate the clinicopathological predictors of survival in patients with intrahepatic cholangiocarcinoma, mass-forming type (ICC-MF), following curative intent hepatectomy. Methods: Clinical characteristics and outcomes were analyzed in a series of 42 patients who underwent curative hepatectomy for ICC-MF between February 1987 and December 2012. The relationship between immunohistochemical expression profiles of mucin (MUC) core proteins (MUC2, MUC5AC, and MUC6) and surgical outcomes was examined Results: The overall median follow-up period was 2.6 years (0.2-17.9). Bile duct reconstruction (p = 0.017), lymph node metastasis (p = 0.049), maximal mass diameter >= 5.0 cm (p = 0.002), and MUC5AC expression (p = 0.003) were identified as significant adverse predictors of overall survival by univariate analysis. Bile duct reconstruction (p = 0.048), maximal mass diameter >= 5.0 cm (p = 0.002), and MUC5AC expression (p = 0.005) were found to be independent predictors of poor prognosis by multivariate analysis. Maximal mass diameter >= 5.0 cm (p = 0.011) was found to be an independent predictor for the tumor recurrence. There was a strong correlation between MUC5AC expression and lymph node metastasis (p = 0.021). MUC6 expression was more frequent in patients with concurrent MUC5AC expression (p = 0.019). Conclusions: MUC5AC expression was significantly related to long-term prognosis and aggressive tumor development, and may be a useful prognostic marker. (C) 2015 Elsevier Ltd. All rights reserved.