Pathological aspects of mucinous cholangiocarcinoma: A single-center experience and systematic review.

Cholangiocarcinoma is a malignant neoplasm originating from the biliary epithelium. Its incidence is highest in Southeast Asia, especially in Thailand. Mucinous intrahepatic cholangiocarcinoma (mucinous iCCA), characterized by an abundant extracellular mucin pool accounting for at least 50% of total tumor volume, is an extremely rare variant of such malignancy and is notorious for rapid progression and dismal prognosis. We conducted an 11-year retrospective analysis of resected mucinous iCCAs from our institution with a systematic review on mucinous iCCAs and combined hepatocellular-mucinous cholangiocarcinoma (cHCC-mCCA). There were four resected mucinous iCCA specimens at our institution (prevalence = 0.5%). Most of the patients were male. The clinicopathological characteristics were variable. The diagnosis of mucinous iCCAs could not be rendered without pathological evaluation. Either intraductal papillary neoplasm or biliary intraepithelial neoplasia was present in three out of four cases. One patient passed away at 11 months following liver resection. A total of 19 mucinous iCCAs and four cHCC-mCCAs from previously published literature were analyzed. The 1-year mortality rate of mucinous iCCAs from our series and published literature is 35%. The present study confirmed that mucinous iCCA is an exceedingly uncommon variant of iCCA. The differential diagnoses include metastatic carcinoma with mucinous component and cHCC-mCCA.