Cholangiocarcinoma
Todd M. Blodgett, MD
Alex Ryan, MD
Omar Almusa, MD
Key Facts
Terminology
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Malignancy that arises from ductular epithelium of intrahepatic biliary tree, extrahepatic bile ducts
Imaging Findings
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PET: Hypermetabolic activity corresponding to primary tumor in liver, extrahepatic metastatic disease
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Ultrasound (US), CT, MR: For hilar lesions (Klatskin tumor), bile duct obstruction with small central mass
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Extrahepatic tumors (87-92% of CC): Proximal, middle, distal ductal tumors
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PET for staging distant metastases; characterizing peripheral CC
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Delayed enhancement with increasing attenuation seen in up to 74% of lesions, usually ↑ CT sensitivity/specificity
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Hilar CC: Low FDG activity with focal nodular or linear branching pattern
Top Differential Diagnoses
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Hepatocellular Carcinoma (HCC)
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Primary Sclerosing Cholangitis (PSC)
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Focal Nodular Hyperplasia (FNH)
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Cavernous Hemangioma
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Pancreatic Carcinoma
Clinical Issues
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Obstructive jaundice (90%)
Diagnostic Checklist
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Ability of PET to detect distant metastases alters surgical management (reportedly up to 30% of cases)
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PET sensitivity for distant mets 65-70%
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PET sensitivity for regional or hepatoduodenal mets is approximately 13%
TERMINOLOGY
Abbreviations and Synonyms
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Cholangiocarcinoma (CC), Klatskin tumor, malignant bile duct tumor
Definitions
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Malignancy that arises from ductular epithelium of intrahepatic biliary tree and extrahepatic bile ducts
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Note: Gallbladder cancer 9x more common than CC
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Klatskin tumor: Perihilar cholangiocarcinoma involving bifurcation of hepatic duct; accounts for more than 70% of all bile duct cancers
IMAGING FINDINGS
General Features
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Best diagnostic clue
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PET: Hypermetabolic activity corresponding to primary tumor in liver, extrahepatic metastatic disease
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Ultrasound, CT, MR: Bile duct obstruction w/small central mass suggests hilar lesion (Klatskin tumor)
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Location
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Extrahepatic tumors (87-92% of CC): Proximal, middle, distal ductal tumors
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Extrahepatic tumor at bifurcation of proximal common hepatic duct = Klatskin tumor
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Intrahepatic tumors (8-13% of CC) arise from small ducts
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Nodular or papillary type is most common in distal duct and periampullary region
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Intrahepatic tumors have tendency for perineural spread, but spread to liver, peritoneum, lung is extremely rare
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Extrahepatic tumors spread to celiac nodes in ˜ 16% of cases
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Size
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Peripheral lesions are usually larger, measuring 5-20 cm at presentation
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More central lesions (Klatskin) smaller at diagnosis
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Morphology
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Variable
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Most intrahepatic CC present as mass, whereas 90% of extrahepatic CC reveal diffusely infiltrating growth pattern
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Imaging Recommendations
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Best imaging tool
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CT: Staging regional/distant metastases; similar to US for demonstrating ductal dilation, large mass lesions
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MRCP/ERCP: Sensitivity of 71-81% for detecting tumor in malignant stenoses, particularly central lesions
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PET for staging distant metastases and characterizing peripheral CC
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ERCP with brush cytology, DNA analysis, and serum analysis of CA 19-9 and CEA for initial workup
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Have been shown to increase sensitivity significantly
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Diagnosis of CC, especially in primary sclerosing cholangitis (PSC), may remain uncertain until invasive and aggressive approaches such as exploratory laparotomy provide biopsy
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Protocol advice
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Delayed PET imaging at ˜ 120 minute time point shown to better discriminate tumor from inflammation
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Delayed imaging helps differentiate tumor from background liver activity
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CT Findings
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NECT
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Mass predominantly hypoattenuating with irregular margins
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Intrahepatic biliary duct (IHBD) dilation common with obstruction
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Larger peripheral lesions may be isodense with central low attenuation and scarring
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Central and satellite lesions
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Hilar masses often not visible on NECT
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IHBD dilation = clue
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Capsular retraction may reveal intrahepatic tumor
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Large common duct (extrahepatic) masses may be identified on NECT
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CECT
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Solitary, small, well-demarcated tumors are difficult to differentiate from primary hepatocellular carcinoma (HCC)
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Arterial phase: Peripheral CC seen as intrahepatic mass showing early peripheral rim enhancement and progressive patchy central enhancement
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Portal phase: Portal vein invasion, ductal wall thickening with minimal enhancement, and portal lymphadenopathy
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Delayed phase
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Enhancement with increasing attenuation seen in up to 74% of lesions, usually ↑ CT sensitivity/specificity
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Persistent tumor enhancement due to fibrous stroma
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Low reported sensitivity for small hilar lesions (approximately 50%)
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Regional lymph node spread rarely detected (24-40% of cases)
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Nuclear Medicine Findings
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FDG PET
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Primary uses
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Identification of new lesions
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Evaluation of metabolic activity and associated malignancy
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Characterization of response to neoadjuvant therapy
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Detection of lesions in liver that are not suspected on US or MR in up to 50% of patients
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Peripheral CC: Intensely hypermetabolic activity, may be ring-shaped
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Hilar CC: Low activity with focal nodular or linear branching pattern
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Lower FDG uptake may be related to tumor size or arrangement of fibrous stroma and mucin pool in tumor
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Can be difficult to discriminate between extrahepatic tumor itself and FDG-accumulating lymph nodes in perihilar region
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Extrahepatic CC may have low uptake due to loosely connected cell nests and poor detection with PET due to infrequency of evident mass formation
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PET sensitivity
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61-90% for primary CC
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85% for nodular CC
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18% for infiltrating CC
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65-70% for distant metastases
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Only 13% for regional or hepatoduodenal mets
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False negatives are seen with mucinous adenocarcinomas (rare)
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False positives are seen due to foci of inflammation (e.g., intrahepatic stone)
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Uptake likely to be seen along tract of biliary stents
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Primary sclerosing cholangitis (PSC)
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PET can be used to discriminate between PSC with and without CC
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Not reliable for early diagnosis of CC in patients with PSC
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Liver in patients with PSC may have ↑ background signal than those of healthy control patients
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PET/CT
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Allows better identification of non-FDG avid tumors & carcinomatosis and helps distinguish stent-related uptake from malignant disease
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Shown to change oncological management in up to 17% of patients
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No diagnostic advantage over CECT in detection of intrahepatic CC or primary tumor site of extrahepatic CC
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Generally cost-effective method, avoids unnecessary surgery
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Hepatobiliary scintigraphy: Focal photopenic lesion
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Tc-99m sulfur colloid: Focal photopenic lesion
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Ga-67 scintigraphy: Variable Ga-67 uptake
DIFFERENTIAL DIAGNOSIS
Hepatocellular Carcinoma (HCC)
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NECT typically shows an iso- or hypodense mass
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Shows early enhancement on CECT (vs. late enhancement in CC)
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Variable FDG uptake with ˜ 50% having little/no FDG uptake due to ↑ glucose-6-phosphatase
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