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Page 2 of 15 Della Corte et al. Hepatoma Res 2022;8:5 https://dx.doi.org/10.20517/2394-5079.2021.103

Based on their anatomical localization, CCs are subdivided into intrahepatic cholangiocarcinoma (ICC)
(i.e., originating from intrahepatic bile ducts) and extrahepatic cholangiocarcinoma (ECC). ECCs are
further subdivided into perihilar- (peCC) and distal-extrahepatic cholangiocarcinoma (deCC) depending on
its proximal or distal origin with respect to the confluence of the cystic duct into the main bile duct.

Morphologically, CCs are subdivided into mass-forming, periductal-infiltrating, or intraductal-growth, with
intrinsic imaging findings and prognostic outcome. Intraductal-growth CCs tend to have a better prognosis,
while mass-forming and periductal infiltrating types appear to have a poor outcome.

[2]
The global incidence of CC varies from 0.3 to 6 per 100,000 inhabitants per year , and similarly, the
mortality ranges from 1 to 6 inhabitants per 100,000 per year . Both CC incidence and mortality have been
[3]
increasing in the past few decades, representing a relevant health burden.

Risk factors for development of CC are present in approximately 50% of cases. These risk factors vary
according to geographical distribution as well as anatomical location. Diseases affecting the peripheral bile
ducts, such as choledocholithiasis and primary sclerosing cholangitis, are more strongly associated to ECC;
whereas, intrahepatic conditions, such as cirrhosis (i.e., viral or NASH-related) and intrahepatic lithiasis, are
[4]
more typically linked to ICC . Accordingly, patient age at diagnosis shows extreme variability, ranging
from 2nd decade of life in the case of Cairoli disease to the 6th decade of life in NASH-related forms .
[6]
[5]
Comorbidities typical of CC patients, including but not limited to reduced liver function and cholestasis,
[7]
may influence prognosis , as well as treatment selection whenever they contribute to patient unfitness for
surgery.
CC imaging requires in-depth knowledge of disease specific characteristics, as cases may present with
atypical imaging features or “conventionally” described characteristics may mimic other malignancies or
[8]
benign lesions [9,10] . Imaging evaluation of specific sub-group characteristics is therefore of paramount
importance for disease diagnosis and therapeutic approach assessment. To date, computed tomography
(CT) and magnetic resonance imaging (MRI), aided by magnetic resonance cholangiopancreatography
(MRCP) sequences, remain the most commonly used imaging modalities. Positron emission tomography
(PET) [11,12] may be useful for detection of metastases and may be of aid in further personalizing treatment
options. In addition to diagnosis and resectability assessment, imaging may aid in providing information
about prognosis of CCs, by combining information deriving from morphology, enhancement pattern, and
texture analysis along with clinical and histopathological data.

Regarding treatment, surgical resection with negative margins is recognized as the only curative treatment
for both ICC and ECC . Several limitations, including disease stage, inadequate future liver remnant,
[13]
presence of metastases, and technical contraindications, lower resectability rate to 20%-30% [14,15] . In patients
with unresectable ICC, loco-regional treatment options are valid alternatives to systemic chemotherapy and
have been shown to increase overall survival [16,17] . The most common techniques are ablative and intra-
arterial therapies. Recent evidence also supports these approaches and suggests a role for loco-regional
treatments in the adjuvant and neo-adjuvant setting. Combined approaches can also be used when imaging
and histopathology identify the need to confirm negative margins in patients with non-upfront surgical
resection . For ECC, the role of the interventional radiologist is mostly limited to the palliative and
[18]
ancillary setting (i.e., biliary drainage/stent positioning and hypertrophy-inducing techniques to allow
[19]
surgical resection), without direct effects on disease burden .