A case of mucinous cholangiocarcinoma showing features of hepatocellular carcinoma

Combined hepatocellular-cholangiocarcinoma and its mimickers: Diagnostic pitfalls in surgical pathology

BACKGROUND

The diagnosis of combined hepatocellular-cholangiocarcinoma (cHCC-CCA) requires histomorphological detection of both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). However, these primary liver cancers (PLCs) have a wide variety of microscopic appearances resulting in difficulties and uncertainties in cHCC-CCA's diagnosis. This study aims to perform a clinicopathologic analysis on the diagnosis of PLCs at a tertiary referral hospital in Thailand using traditional morphologic studies.

METHODS

A 5-year retrospective analysis of pathologically diagnosed PLCs was conducted. Pathological features and clinical characteristics of cHCC-CCA and other PLCs with the histopathologic resemblance to cHCC-CCA were studied. The pathological diagnosis was rendered based on histomorphological context rather than immunoreactivity. A literature review containing diagnostic pitfalls of cHCC-CCA was carried out.

RESULTS

PLCs from a total of 295 patients were retrieved, and cHCC-CCA accounted for 1.4% (n = 4) of the malignancies. Histomorphological evaluation is the most reliable diagnostic modality for cHCC-CCA. Extremely uncommon variants of iCCA (i.e., mucinous iCCA and adenosquamous iCCA) and iCCA arising with hepatocellular nodular lesions (i.e., iCCA with nodular regenerative hyperplasia (NRH), and iCCA in cirrhosis) could have a histomorphologic resemblance to that of cHCC-CCA.

CONCLUSIONS

Although there has been an exceedingly high incidence of iCCA in Thailand, such a commonness is not valid for cHCC-CCA in our series. Rare forms of iCCA could have a morphologic resemblance to that of cHCC-CCA. Regardless of the differentiation and immunophenotype, iCCA without a distinct HCC component should never be diagnosed as cHCC-CCA.

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.

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.

Mucinous cholangiocarcinoma: Clinicopathological features of the rarest type of cholangiocarcinoma

Mucinous cholangiocarcinoma is extremely rare and its clinicopathological features remain unclear. The present study aimed to analyze published data on mucinous cholangiocarcinoma. Medical databases were searched from 1980 to 2016, and clinicopathological data for 16 mucinous cholangiocarcinoma patients were obtained. Characteristic imaging findings, including hypovascular tumor with peripheral enhancement on computed tomography and angiography, extremely high intensity on T2-weighted magnetic resonance images, intratumoral calcification and luminal communication between the tumor and bile duct on cholangiography, were noted. Mucinous cholangiocarcinoma was correctly diagnosed in one patient only, with some patients diagnosed as low-malignant biliary cystic tumors preoperatively. Five cases were followed up after the first medical examination, and three of these were initially diagnosed as biliary cystadenoma or intraductal papillary neoplasm of the bile duct. All five tumors showed marked enlargement within 4 months of follow up. Macroscopically, the resected tumors were non-cystic/solid in seven cases, and cystic in seven. Tumor diameter ranged from 5 cm to 22 cm, and mucoid cut surface, lobulation, lack of capsule and papillary growth were observed. Microscopically, co-existing intraductal papillary neoplasm of the bile duct was noted in three of five patients with available data. Nine of 10 cases in whom the pathological stage was reported had advanced disease with lymph node and/or distant metastasis, and 5-year survival was achieved in one microinvasive case only. Overall 1- and 3-year survival rates were 60.1% and 40.1%, respectively. The possibility of mucinous cholangiocarcinoma should be considered when biliary cystic tumors are detected on imaging modalities, despite the rarity of this tumor.