Resected primary mucinous cholangiocarcinoma of the liver

BACKGROUND: Mucinous cholangiocarcinoma (MC) is a very rare variant of intrahepatic cholangiocarcinoma. MC is characterized by rapid growth, widespread metastasis, and poor prognosis. We report a case of resected MC of the liver. CASE PRESENTATION: We found a 13.6-cm hypovascular tumor in the left hepatic lobe of a 68-year-old man, which we initially diagnosed as a mass-forming intrahepatic cholangiocarcinoma. Left lobe and caudate resection was performed without major intraoperative or postoperative complications. He was discharged home on postoperative day 9 and had no recurrence for 6 months. Pathological examination showed a mucous lobulated tumor with abundant mucus in the cytoplasm and extracellular regions. After differential diagnosis that considered invasive intraductal papillary neoplasm of the bile duct and metastatic liver tumors from the digestive tract, this tumor was diagnosed as a cholangiocarcinoma rare variant: primary mucinous carcinoma of the liver. CONCLUSION: Analysis of previous reports suggests that primary MC of the liver could be classified into two subtypes: pure MC and combined hepatocellular carcinoma and MC. Notably, the latter has been reported only in patients with chronic liver disease, whereas the former has only been reported in patients with no underlying disease.