Cholangiohepatoma

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Cholangiohepatoma, also referred to as mixed hepatocellular cholangiocarcinoma (HCC-CC), refers to synchronous cholangiocarcinoma and hepatocellular carcinoma (HCC) in the same tumor. It is a rare and aggressive primary hepatic tumor combination. The origin of cholangiohepatoma is closely linked to the origin of cholangiocarcinoma rather than HCC.

Terminology

HCC-CC is defined when both histological types are found within the same hepatic tumor, therefore, it does not apply for synchronous separated hepatocellular and cholangiocellular carcinomas. Also, fibrolamellar carcinoma and hepatoblastoma are not included in the current definition of HCC-CC .

Epidemiology

The incidence of HCC-CC varies between 0.4 and 4.7%.

Clinical presentation

Most commonly, these tumors develop asymptomatically until they become more advanced. Then they can manifest with right upper quadrant pain, weight loss, and obstructive jaundice.

The alpha-fetoprotein (AFP), serum marker for HCC, and carbohydrate antigen 19-9 (Ca 19-9), serum marker for cholangiocarcinoma, may be elevated. AFP levels tend to be lower in HCC-CC when compared to HCC .

Pathology

Etiology

Histogenesis of the tumor is thought to occur at the canal of Hering:

  • the canals of Hering (CoH) or intrahepatic bile ductules are found near the outer edge of a liver lobule
  • they are lined partially by cholangiocytes and partly by hepatocytes
  • hepatic stem cell niches (hepatic progenitor cells) have been identified in the canals of Hering
  • they can differentiate into hepatocytes and cholangiocytes and can, therefore, give rise to HCC, cholangiocarcinoma, and cholangiohepatoma sharing features of both HCC and cholangiocarcinoma
Microscopic appearance
  • conventional histology may be inconclusive
  • 2010 WHO classification divides HCC-CC tumors into two types
    • classical: histologically characterized by typical areas of HCC together with those of cholangiocarcinoma in the same tumor
    • with stem cell features
Immunohistochemistry

Glypican-3 is highly sensitive and specific for identification of HCC component and only weakly reactive with cholangiocarcinoma. Biliary cell stains are mucin, CK7, and CK19, whereas hepatocellular stains comprise polyclonal CEA, Hep Par 1, and CD10.

Radiographic features

Imaging features are a combined spectrum of intrahepatic cholangiocarcinoma and hepatocellular carcinoma.

Ultrasound

Heterogeneous iso-to-hyperechoic mass with a peripheral hypoechoic halo of the compressed liver. Capsular retraction and lobulated appearance with infiltration of the biliary system are usually seen. Ultrasound appearance is non-specific and usually parallels that of conventional cholangiocarcinoma.

CT
  • the lesion is usually lobulated and well delineated, although a well-defined capsule is not seen
  • hepatic capsular retraction and infiltration of the biliary tree are usually seen
    • biliary obstruction disproportionate to that expected for the tumor size
  • post contrast imaging
    • progressive delayed enhancing areas mixed with areas arterial enhancement and washout is very suggestive of cholangiohepatoma
MRI

MRI features of cholangiohepatoma have not been described extensively.

Signal characteristics:

  • T1: low signal
  • T2: intermediate-to-high signal intensity +/- central hypointense focus
  • DWI/ADC: marked restricted diffusion
  • T1C+: progressive delayed enhancing areas mixed with areas arterial enhancement and washout

MR imaging with a hepatocellular agent like gadoxetic acid may also be useful to differentiate cholangiohepatoma and cholangiocarcinoma.

Treatment and prognosis

The prognosis of cholangiohepatoma is poor, even with resection.

Differential diagnosis

Possible differential considerations include: