MUC5AC and cholangiocarcinoma: Goodman et al. proposed a new classification into the three groups of “collision tumors” (Type I), which reflects an apparent coincidental occurrence of both hepatocellular carcinoma and cholangiocarcinoma in the same patient, "transitional tumors” (Type II), in which there are areas of intermediate differentiation and an identifiable transition between hepatocellular carcinoma and cholangiocarcinoma and “fibrolamellar tumors” (Type III), which resembled the fibrolamellar variant of hepatocellular carcinoma but bears mucin-producing pseudoglands [59].