Small cholangiolocellular carcinoma that was difficult to distinguish from cholangiocellular carcinoma: a case report

BACKGROUND: Cholangiolocellular carcinoma (CoCC) is thought to be derived from hepatic progenitor cells. Because of its origin, CoCC has diverse clinicopathological and imaging findings. Here, we report a case of small CoCC that was difficult to diagnose preoperatively. CASE PRESENTATION: A 62-year-old woman was confirmed with a small liver nodule in the left lobe 2 years after a sustained virological response of hepatitis C virus. The size of the nodule was 11.9 × 6.1 mm, and 6 months later, the size increased to 12.5 × 7.8 mm. The doubling time of this tumor was 285 days. The tumor revealed peripheral early enhancement and delayed internal staining in dynamic computed tomography images and marked high intensity in diffusion-weighted magnetic resonance imaging scans. These imaging findings resembled those of cholangiocellular carcinoma (CCC). The tumor was removed by laparoscopic lateral sectionectomy. Pathological findings revealed that the tumor was composed of small cuboidal cells and showed irregular anastomosis small grand. Immunohistochemical findings showed that the tumor cells were negative for Hep-par 1 and positive for cytokeratin 19. Epithelial membrane antigen staining was positive for the membranous side of the lumen. According to these pathological findings, the tumor was diagnosed as CoCC. CONCLUSION: Although some characteristic imaging findings are reported for CoCC, they are not specific because of the variety in pathological findings. Especially, small CoCCs might have poor characteristic imaging findings and may be difficult to distinguish from CCC in the images. However, slow tumor growth might be one of the characteristics to suspect the possibility of a CoCC.