Combined hepatocellular-cholangiocarcinoma (cHCC-CC) is a rare primary liver malignancy harboring features of both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) within the same tumor. It accounts for 1-5% of all primary liver cancers. The coexistence of imaging features of both components — arterial hypervascularity (HCC component) combined with fibrous stroma and delayed enhancement (ICC component) — provides diagnostic clues, but accurate preoperative diagnosis is extremely difficult. The tumor can develop in the setting of cirrhosis and AFP may be elevated (HCC component). Prognosis is worse than pure HCC and closer to pure ICC — with high tendency for early lymph node metastasis and intrahepatic spread. In the 2019 WHO classification, cHCC-CC is defined as a separate entity requiring histological demonstration of both differentiations.
Age Range
50-75
Peak Age
60
Gender
Male predominant
Prevalence
Rare
The pathogenesis of cHCC-CC is debated, but the most accepted theory is the bipotent hepatic progenitor cell (oval cell) hypothesis. Hepatic progenitor cells have the capacity to differentiate into both hepatocytes and cholangiocytes; malignant transformation of these cells produces a tumor showing differentiation in both directions. Alternatively, cholangiolar transdifferentiation within existing HCC or hepatocellular transdifferentiation within ICC has been proposed. The HCC component contains arterial neovascularization — therefore shows arterial phase enhancement and may exhibit washout in portal/delayed phases. The ICC component contains dense fibrous stroma (desmoplasia) — contrast diffuses slowly into fibrous tissue creating delayed phase enhancement. The coexistence of these two different contrast kinetics is the diagnostic key finding of cHCC-CC. Peripheral biliary dilatation results from the ICC component obstructing bile canaliculi — this finding is not expected in pure HCC. The dual phenotype of the tumor has important implications for prognosis and treatment: local treatments targeting HCC (ablation, TACE) may not adequately control the ICC component.
Coexistence of washout in the HCC component and delayed enhancement in the ICC component within the same tumor — this dual kinetic pattern is the most specific finding for cHCC-CC and is not seen in pure HCC or pure ICC. The delayed phase best demonstrates these two opposite kinetic behaviors.
In the arterial phase, the tumor shows heterogeneous enhancement: regions corresponding to the HCC component demonstrate prominent arterial hypervascularity (APHE), while regions corresponding to the ICC component are hypovascular or show minimal enhancement. This 'mosaic' enhancement pattern is the most characteristic arterial phase finding of cHCC-CC. The tumor is usually not well-defined and may have irregular contours.
Report Sentence
In the arterial phase, the mass shows heterogeneous enhancement with focal areas of prominent arterial enhancement (HCC component) coexisting with hypovascular areas (ICC component).
In the delayed phase, a dual kinetics pattern is observed: areas corresponding to the HCC component show washout (hypointensity in portal/delayed phase), while areas corresponding to the ICC component show progressive delayed enhancement (hyperintensity). This 'dual kinetics' is the most diagnostic CT finding for cHCC-CC — not seen in pure HCC or pure ICC.
Report Sentence
In the delayed phase, the mass exhibits dual kinetics with washout in some areas (HCC component) and progressive delayed enhancement in other areas (ICC component).
On T2-weighted imaging, the tumor shows heterogeneous signal: the HCC component is moderately hyperintense; the ICC component is more markedly hyperintense or shows a target pattern (peripheral hyperintense, central hypointense — fibrous stroma). T2 target sign suggests the presence of ICC component and is defined as 'target' morphology in LI-RADS — this finding is not expected in pure HCC.
Report Sentence
On T2-weighted sequence, the mass shows heterogeneous signal with a peripheral hyperintense, central hypointense target pattern (consistent with ICC component).
On hepatobiliary phase (gadoxetic acid), the tumor is predominantly hypointense — neither HCC nor ICC components show OATP uptake. However, in some cHCC-CCs, focal and irregular iso/hyperintense areas ('cloud-like enhancement') may be seen in the HCC component — reflecting differentiation heterogeneity of progenitor cell origin.
Report Sentence
On hepatobiliary phase, the mass shows predominantly hypointense signal with focal irregular iso/hyperintense areas (consistent with dual phenotype).
On DWI, the tumor shows heterogeneous diffusion restriction. The HCC component demonstrates prominent DWI hyperintensity and low ADC, while fibrous stroma-dominant areas of the ICC component show less prominent diffusion restriction. Heterogeneous values on ADC map — low ADC areas (cellular HCC) and moderate ADC areas (fibrous ICC stroma) coexist.
Report Sentence
On DWI, the mass shows heterogeneous diffusion restriction with coexisting low and moderate ADC value areas on the ADC map.
On B-mode ultrasonography, a heterogeneously echogenic mass is observed. The mass may contain both hypoechoic (HCC component) and isoechoic/mildly hyperechoic areas (ICC stroma). Dilatation of peripheral bile ducts adjacent to the tumor is noteworthy — this finding is not expected in pure HCC and suggests the ICC component.
Report Sentence
A _x_ cm heterogeneously echogenic mass is seen in liver segment _ with notable dilatation of bile ducts adjacent to the tumor.
Criteria
HCC and ICC components exist as separate, recognizable regions within the tumor. Each component retains its own histological and imaging features. Unlike collision tumor, same progenitor cell origin.
Distinct Features
Most diagnostic type on imaging — mosaic enhancement and dual kinetics pattern most clearly seen in this type.
Criteria
Expression of progenitor/stem cell markers (CK19, EpCAM, CD56). Both components intermingled and difficult to separate. More aggressive behavior and worse prognosis.
Distinct Features
More homogeneous and less distinctive on imaging — may be confused with pure HCC or ICC. Definitive diagnosis by immunohistochemistry.
Criteria
HCC component constitutes the majority of the tumor (>70%). ICC component is focal and small. On imaging, dominant arterial hypervascularity + focal delayed enhancement.
Distinct Features
May be misdiagnosed as pure HCC preoperatively. Detection of ICC component by frozen section during surgery may change treatment plan.
Distinguishing Feature
In pure HCC, the entire mass shows arterial APHE + washout; delayed enhancement is not expected. In cHCC-CC, washout and delayed enhancement coexist in the same lesion. Biliary dilatation is rare in pure HCC; may be seen in cHCC-CC due to ICC component. In LI-RADS, target morphology suggests non-HCC malignancy.
Distinguishing Feature
In pure ICC, arterial hypervascularity is not expected (hypovascular rim enhancement is typical); in cHCC-CC focal arterial hypervascularity is seen. AFP is normal in pure ICC; may be elevated in cHCC-CC due to HCC component. Pure ICC is entirely hypointense on hepatobiliary phase; focal iso/hyperintense areas ('cloud') may be seen in cHCC-CC.
Distinguishing Feature
T2 target sign is not expected in pure HCC — HCC typically shows homogeneous/mildly heterogeneous T2 hyperintensity. In cHCC-CC, T2 target pattern (peripheral hyperintense, central hypointense) is seen due to ICC component. This finding directs to LR-M category for non-HCC malignancy in LI-RADS.
Distinguishing Feature
EHE typically shows multiple, peripheral, target-like enhancing lesions; cHCC-CC is usually a solitary large mass. AFP is normal in EHE, no cirrhosis association. 'Capsular retraction' (lollipop sign) is pathognomonic for EHE; not expected in cHCC-CC.
Urgency
urgentManagement
surgicalBiopsy
NeededFollow-up
3-monthSurgical resection is the primary treatment for cHCC-CC — however, lymph node dissection is more important than in pure HCC due to the presence of ICC component. Local treatments targeting HCC such as TACE or ablation may not adequately control the ICC component. Liver transplantation is controversial — recurrence risk is high due to ICC component and some centers consider it contraindicated. Prognosis is worse than pure HCC (5-year survival 30-40%). Postoperative follow-up with CT/MR every 3 months is recommended. Since accurate preoperative diagnosis is difficult, biopsy should be considered — but sampling error risk exists (only one component may be captured).
Diagnosis of combined tumor directly impacts treatment planning. Unlike pure HCC, liver transplantation is generally not appropriate. Resection is the primary treatment option. Prognosis is worse compared to pure HCC or ICC.