A clinicopathological study on combined hepatocellular and cholangiocarcinoma.

We clinicopathologically studied 23 surgically resected cases of combined hepatocellular and cholangiocarcinoma (HCC-CC). The frequency of this cancer in our subjects, who had primary liver cancer and who underwent hepatectomy, was 6.3%. The mean age of patients was 64.0 years old and the male: female ratio was 1.9:1. Serum alpha-fetoprotein was positive in 70% of cases and its levels were relatively low (< or = 1000 ng/mL) in most cases. The positive rate of serum carcinoembryonic antigen was 18% and its levels were also low. In regard to hepatitis virus markers, 17% of the 20 combined HCC-CC cases were positive to HBs antigen and 70% were positive to the HCV antibody. Of the 23 combined HCC-CC cases, 9 cases (39%) were associated with liver cirrhosis. Tumours were classified macroscopically into a separated type (HCC and CC are clearly separated 17%), a HCC-predominant type (resembles HCC 49%), and a CC-predominant type (resembles CC 34%). The separated and HCC-predominant types were associated with liver cirrhosis in 50 and 55% of cases, respectively. These cases with liver cirrhosis presented the features of HCC more apparently, while those without liver cirrhosis presented the features of CC. Histologically, all cases were classified into either Type I (HCC and CC were clearly distinguished; 17%), Type II (HCC and CC were contiguous and shared transitional features; 66%), and Type III (cancer cells were able to be evaluated as either HCC or CC and were considered to be an intermediate type; 17%). Immunohistological stains for cytokeratin were useful to distinguish HCC and CC. Specifically, CC was positive to cytokeratin 7 and 19. The tumour, in which HCC and CC were almost indistinguishable, such as Type III), indicates the presence of intermediate tumour cells that can differentiate either to HCC or CC.