Hilar cholangiocarcinoma (Klatskin tumor) is a bile duct carcinoma arising at the hepatic duct confluence (junction of right and left hepatic ducts). It is the most common type, constituting 50-70% of all cholangiocarcinomas and representing the majority of extrahepatic biliary malignancies. Staged according to Bismuth-Corlette classification as Type I-IV, which determines surgical resectability. Clinically presents with obstructive jaundice, weight loss, and pruritus. MRCP characteristically shows stricture at the hepatic duct confluence with bilateral intrahepatic biliary dilation. CT and MRI evaluate periductal infiltrative mass, delayed enhancement, and vascular invasion. PSC, hepatolithiasis, Caroli disease, and chronic biliary infections are risk factors. Surgical resection is the only curative option but only 30-50% of patients are resectable at diagnosis.
Age Range
45-80
Peak Age
65
Gender
Male predominant
Prevalence
Uncommon
Hilar cholangiocarcinoma is an adenocarcinoma arising from bile duct epithelium, following the chronic biliary inflammation → dysplasia → carcinoma sequence. The tumor characteristically shows periductal infiltrative growth pattern accompanied by intense desmoplastic reaction (fibrous stroma) — therefore imaging shows stricture and wall thickening rather than a large mass. The desmoplastic stromal component shows minimal early-phase enhancement due to low vascularity and high collagen content, while progressive enhancement appears in delayed phase as fibrous tissue slowly retains contrast agent. The tumor obstructs the hepatic duct confluence causing bilateral intrahepatic biliary dilation — abrupt interruption of dilated intrahepatic ducts at the confluence ('pruned tree' appearance) on MRCP is characteristic. The Bismuth-Corlette classification defines invasion extent: Type I (below confluence), Type II (at confluence), Type IIIa/b (unilateral sectoral extension), Type IV (bilateral sectoral involvement). Portal vein and hepatic artery invasion is facilitated by periductal spread as these vascular structures are anatomically adjacent to bile ducts.
Abrupt termination of dilated intrahepatic bile ducts at the hepatic duct confluence on MRCP — resembling a tree with pruned branches. Characteristic finding of hilar cholangiocarcinoma on MRCP that directly shows the obstruction level. Forms the basis of Bismuth-Corlette typing.
Abrupt stricture at the hepatic duct confluence with bilateral dilation of proximal intrahepatic bile ducts on MRCP. Dilated ducts abruptly terminate or severely narrow at the confluence level — 'pruned tree' appearance. According to Bismuth-Corlette classification: Type I shows single stricture below confluence, Type II at confluence level, Type IIIa/b extends to right or left hepatic duct, Type IV extends to bilateral sectoral ducts. Distal CBD is usually normal caliber (negative Courvoisier).
Report Sentence
Abrupt stricture at the hepatic duct confluence with bilateral intrahepatic biliary dilation is identified on MRCP, consistent with hilar cholangiocarcinoma (Klatskin tumor); Bismuth-Corlette Type ... level.
Periductal infiltrative mass around bile ducts in the hilar region shows progressive enhancement on delayed phase CT (3-5 minutes). The mass shows minimal or moderate enhancement in arterial and portal venous phases but gains marked enhancement in delayed phase. This enhancement pattern reflects the tumor's dense desmoplastic fibrous stroma. The mass is usually small (<3 cm) and large mass formation is rare — periductal growth pattern is dominant.
Report Sentence
Periductal infiltrative soft tissue around bile ducts in the hilar region showing progressive delayed phase enhancement is identified, consistent with hilar cholangiocarcinoma.
Assessment of portal vein and hepatic artery invasion on portal venous phase is critical for surgical resectability. Portal vein invasion: narrowing by tumor (>180° circumferential involvement = unresectable), irregular contour or occlusion. Hepatic artery invasion: caliber irregularity or occlusion. Unilateral portal vein invasion leads to ipsilateral hepatic lobe atrophy (atrophy-hypertrophy complex). Contralateral lobe shows compensatory hypertrophy.
Report Sentence
Tumoral ensheathment/invasion of portal vein branches in the hilar region should be evaluated; portal vein invasion directly affects surgical resectability.
Periductal infiltrative soft tissue of intermediate signal intensity around bile ducts in the hilar region on T2-weighted MRI. The mass is usually isointense or mildly hyperintense to liver parenchyma on T2. Marked T2 hyperintensity is not seen due to fibrous stroma content (however, focal T2 hyperintensity may be seen if there is an intramucinous component). Peritumoral biliary dilation is seen as bright T2-signal ducts and indirectly shows tumor extent.
Report Sentence
Periductal infiltrative soft tissue of intermediate signal intensity around bile ducts in the hilar region on T2-weighted sequences is identified, suggestive of hilar cholangiocarcinoma.
Bilateral intrahepatic bile duct dilation with normal caliber distal CBD on ultrasound — indirect indicator of hilar obstruction. The hilar mass is usually not directly visible on US (small periductal infiltrative growth). 'Parallel channel' (shotgun sign) appearance of intrahepatic duct dilation is noteworthy. Gallbladder may be normal or collapsed (gallbladder does not dilate without distal obstruction — negative Courvoisier).
Report Sentence
Bilateral intrahepatic bile duct dilation with normal caliber distal CBD is identified, suggesting hilar level obstruction; further evaluation with MRCP is recommended.
Diffusion restriction in hilar periductal mass on DWI — high signal on high b-value and low signal on ADC map. The cellular component of cholangiocarcinoma shows diffusion restriction while desmoplastic fibrous areas may not — therefore heterogeneous diffusion restriction pattern is typical. DWI adds value to conventional sequences for mass detection as it improves visibility of small periductal infiltrative masses.
Report Sentence
Periductal soft tissue in the hilar region shows diffusion restriction on DWI, a finding supporting cholangiocarcinoma.
Criteria
Stricture below the hepatic duct confluence, in the common hepatic duct. Right and left hepatic ducts are free. Best prognosis.
Distinct Features
Most suitable type for surgical resection. Treated with extrahepatic bile duct resection and hepaticojejunostomy. On MRCP, confluence is open, proximal duct dilation is minimal.
Criteria
Stricture at the hepatic duct confluence level. Right and left hepatic ducts are separately obstructed but sectoral branches are free.
Distinct Features
Complete confluence obstruction on MRCP, bilateral proximal dilation. Requires extrahepatic bile duct + duct confluence resection. Hepatectomy may be needed.
Criteria
Type IIIa: Stricture extends to right hepatic duct (right sectoral branches involved). Type IIIb: Extends to left hepatic duct. Unilateral sectoral branch involvement.
Distinct Features
Extended hepatectomy (right or left) + bile duct resection required. Portal vein invasion determines resectability. Contralateral lobe must have sufficient volume (FLR calculation).
Criteria
Bilateral sectoral duct involvement. Both right and left sectoral branches invaded. Generally considered inoperable.
Distinct Features
Bilateral sectoral duct obstruction demonstrated on MRCP. Surgical resection usually not possible. Biliary drainage + chemotherapy palliative. Liver transplantation may be considered at selected centers.
Distinguishing Feature
In distal cholangiocarcinoma, stricture is in distal CBD (pancreatic segment); both CBD and pancreatic duct may dilate (double duct sign). In hilar type, stricture is at confluence and distal CBD is normal caliber.
Distinguishing Feature
In Mirizzi syndrome, an impacted stone in the gallbladder or cystic duct causes hepatic duct compression; stone appears as hypointense filling defect on MRCP. In cholangiocarcinoma, no stone, periductal infiltrative mass and delayed enhancement.
Distinguishing Feature
In PSC, multifocal strictures and dilations alternate ('beaded' pattern); diffuse involvement rather than single focal stricture is typical. In hilar cholangiocarcinoma, single focal dominant stricture with proximal dilation. Cholangiocarcinoma can develop in PSC — malignancy exclusion needed at dominant stricture.
Distinguishing Feature
In acute cholangitis, diffuse bile duct wall thickening and enhancement, periportal edema, and clinical septic picture (Charcot's triad); no focal mass. In cholangiocarcinoma, focal stricture, delayed-enhancing periductal mass, and usually no septic picture.
Urgency
urgentManagement
surgicalBiopsy
NeededFollow-up
specialist-referralSurgical resection is the only curative option for hilar cholangiocarcinoma. Bismuth Type I-II: bile duct resection + hepaticojejunostomy; Type IIIa/b: extended hepatectomy + bile duct resection; Type IV generally inoperable. Portal vein invasion, bilateral sectoral involvement, and distant metastasis are inoperability criteria. Liver transplantation after neoadjuvant chemoradiation is performed at selected centers for Type IV and locally advanced cases. For inoperable cases, biliary drainage (percutaneous/endoscopic) + chemotherapy (gemcitabine + cisplatin) is palliative. CA 19-9 tumor marker used in follow-up.
Klatskin tumor is an aggressive cholangiocarcinoma. Surgical resection is the only curative treatment but 70% of patients are unresectable at diagnosis. Bismuth-Corlette classification (Type I-IV) is important for surgical planning. Screening and early diagnosis in PSC patients is important.