(Radiographics. 1999;19:1199-1218.)
© RSNA, 1999
Role of US in the Detection, Characterization, and Staging of Cholangiocarcinoma1
Carl M. Bloom, MD, FRCPC,
Bernard Langer, MD, FRCPC and
Stephanie R. Wilson, MD, FRCPC
1 From the Departments of Medical Imaging (C.M.B., S.R.W.) and General Surgery (B.L.), Toronto Hospital, University of Toronto, 200 Elizabeth St, Toronto, Ontario, Canada M5G 2C4. Received August 18, 1998; revision requested October 7 and received December 15; accepted December 15. Address reprint requests to S.R.W.
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Abstract
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Cholangiocarcinoma is a rare tumor with a broad range of pathologic and clinical manifestations that demonstrates a myriad of imaging findings. Recent experience indicates that a more definitive role is possible for ultrasonography (US) in the evaluation of cholangiocarcinoma. Dilatation of the intrahepatic bile ducts is the most frequently seen US abnormality in patients with ductal cholangiocarcinoma. Klatskin tumors classically manifest as segmental dilatation and nonunion of the right and left ducts at the porta hepatis. Papillary and nodular ductal cholangiocarcinoma are relatively easy to see at US: Papillary tumors resemble polypoid intraluminal masses, whereas nodular cholangiocarcinoma manifests as a discrete smooth mass with associated mural thickening. Infiltrating ductal cholangiocarcinoma at the porta hepatis is the most common subtype but is the most difficult to appreciate at US. Peripheral cholangiocarcinoma may be either nodular or infiltrating at US: The nodular form predominates and appears as a solitary mass with a distinct right lobe predilection, whereas the infiltrative form is rare and manifests as a diffusely abnormal liver echotexture. In capable hands, modern high-resolution US equipment with color Doppler imaging capability is highly sensitive in the detection, characterization, and determination of the potential for resectability of cholangiocarcinoma. Thus, use of US may obviate more invasive procedures in some patients and help identify those patients for whom further investigation would be contributory.
Index Terms: Bile ducts, anatomy, 76.92 • Bile ducts, neoplasms, 76.321 • Bile ducts, US, 76.12983
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INTRODUCTION
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Cholangiocarcinoma is a malignant hepatic tumor of the biliary epithelium and represents less than 1% of all newly diagnosed cancers in North America (1). Most of these tumors are adenocarcinomas (95% of cases), some of which produce mucin. Cholangiocarcinoma is mainly a tumor of the elderly, with a peak prevalence during the seventh decade of life and a slight male predilection (2). Predisposing factors include ulcerative colitis, sclerosing cholangitis, Caroli disease, choledochal cyst, liver parasites (Clonorchis [Opisthorchis], Giardia), and exposure to certain chemicals (eg, Thorotrast) (3).
Cholangiocarcinoma is classified as ductal or peripheral depending on its site of origin. Tumors may arise anywhere from the extrahepatic and large intrahepatic bile ducts at the porta hepatis to the smallest bile ductules at the periphery of the hepatic lobule; tumors at the latter site are called peripheral cholangiocarcinomas (4).
Tumors that arise at the convergence of the right and left hepatic ducts are known as hilar cholangiocarcinomas (Klatskin tumors) and account for approximately 10%–26% of all cholangiocarcinomas (4). These tumors may be nodular (ie, small sclerosing tumors that obliterate the duct), infiltrating (ie, tumors that spread along the wall of the duct), or papillary (ie, rare intraductal variants).
Hepatic lobar atrophy with marked biliary dilatation and crowding of bile ducts is seen in almost one-quarter of patients with Klatskin tumors (5). This finding at cross-sectional imaging is strongly suggestive of a hilar tumor with dominant involvement of the duct that supplies the atrophic segment.
Klatskin tumors are often in an advanced stage at the time of diagnosis, and complete resection may be impossible. The most important criteria that may contraindicate surgical resection of hilar cholangiocarcinoma are extensive and bilateral spread through the intrahepatic ducts, involvement of the main trunk or of both branches of the portal vein, vascular involvement on one side of the liver with extensive contralateral bile duct involvement, and hepatic or peritoneal metastasis (6).
Because jaundice is the most common presenting symptom in ductal cholangiocarcinoma, most affected patients initially undergo ultrasonography (US). Early studies of imaging in patients with obstructive jaundice praised the ability of US to allow identification of bile duct dilatation and decried its inability to allow accurate identification of the source of biliary obstruction. However, results of more recent studies, which were carried out with increasingly modern high-resolution equipment, have countered these initial impressions. The sensitivity and specificity of US in the detection of Klatskin tumors have risen dramatically over the past 15 years, from a reported low of 33% in 1983 (7) to a reported high of 96% in 1996 (8).
Our hospital is a tertiary referral center for the evaluation and treatment of cholangiocarcinoma. During the past 15 years, our collective experience in hepatobiliary imaging has provided us with insight into the US evaluation of this tumor. Each year, four hepatobiliary surgeons refer an average of 35 cases of cholangiocarcinoma to our US department. On the basis of our experience, we believe that US is excellent not only for initial identification of cholangiocarcinoma but also for tumor staging and prediction of resectability.
In this article, we describe normal biliary anatomy, optimal US technique in the evaluation of cholangiocarcinoma, various manifestations of the disease at US, and potential pitfalls of this imaging modality.
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NORMAL BILIARY ANATOMY
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Thorough US evaluation of the biliary tree presupposes a knowledge of normal hepatobiliary anatomy and a fastidious and systematic approach to hepatic imaging. Familiarity with the nomenclature commonly used to describe the segmental anatomy of the liver is also necessary for accurate dissemination of information.
The segmental anatomy of the liver as described by Couinaud (9) (Fig 1) and further defined for US applications by Lafortune et al (11) is based on the distribution of the portal and hepatic veins. Each liver segment has a branch of the portal vein at its center and a hepatic vein at its periphery. The liver contains eight segments, four in the left lobe (numbered 1–4) and four in the right lobe (numbered 5–8). The two lobes are separated by the main hepatic fissure, which contains the gallbladder fossa and the middle hepatic vein.
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Figure 1. Couinaud's functional segmental anatomy. The liver is divided into nine segments. The longitudinal boundaries (right, middle, left scissurae) are three hepatic veins. The transverse plane is defined by the right main and left main portal pedicles. (Adapted and reprinted, with permission, from reference 10.)
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US TECHNIQUE
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Examination of the bile ducts should be performed after the patient has fasted for 6 hours so that bowel gas is limited. Most examinations are performed with a 3.5-MHZ convex transducer, with a 5- or 7-MHZ transducer reserved for thin patients. Because many patients have high-riding, entirely subcostal livers, an additional transducer with a small scanning face, which allows an intercostal approach, is often helpful.
US evaluation of the bile ducts should include the following five images:
1. The subcostal oblique view for assessment of the ductal confluence anterior to the portal vein bifurcation at the porta hepatis.
2. The transverse left lobe view for a recumbent H view of the ducts to segments 2–4 (Fig 2).
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Figures 2-5. (2) Recumbent H view of the left portal vein bifurcation. On a subcostal US scan, the left portal vein (p), the ascending branch of the left portal vein (a), and the branches to three segments of the left lobe of the liver (2, 3, and 4) suggest a recumbent H. (3) Recumbent H view of the right portal vein bifurcation. Intercostal oblique US scan shows the branches to the anterior (5 and 8) and posterior (6 and 7) segments of the right lobe of the liver. rpv = right portal vein. (4) Hepatoduodenal ligament view. Sagittal US scan shows the common hepatic duct and common bile duct (CBD) anterior to the main portal vein (MPV). (5) Pancreatic head view. Transverse US scan shows the common bile duct (arrow) along the posterolateral aspect of the pancreatic head. The gastroduodenal artery (arrowhead) courses along the anterolateral aspect of the pancreatic head. PV = portal vein, SV = splenic vein.
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3. The right coronal intercostal view for a recumbent H view of the ducts to segments 5–8 (Fig 3).
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Figures 2-5. (2) Recumbent H view of the left portal vein bifurcation. On a subcostal US scan, the left portal vein (p), the ascending branch of the left portal vein (a), and the branches to three segments of the left lobe of the liver (2, 3, and 4) suggest a recumbent H. (3) Recumbent H view of the right portal vein bifurcation. Intercostal oblique US scan shows the branches to the anterior (5 and 8) and posterior (6 and 7) segments of the right lobe of the liver. rpv = right portal vein. (4) Hepatoduodenal ligament view. Sagittal US scan shows the common hepatic duct and common bile duct (CBD) anterior to the main portal vein (MPV). (5) Pancreatic head view. Transverse US scan shows the common bile duct (arrow) along the posterolateral aspect of the pancreatic head. The gastroduodenal artery (arrowhead) courses along the anterolateral aspect of the pancreatic head. PV = portal vein, SV = splenic vein.
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4. Hepatoduodenal ligament views for assessment of the extrahepatic bile duct from the common hepatic duct to the cephalic aspect of the pancreatic head. A study that begins with the subcostal oblique view of the porta hepatis and continues through the hepatoduodenal ligament to the pancreatic head will show the common hepatic duct and common bile duct anterior to the portal vein in cross section. Turning the transducer 90° will show the length of the common hepatic duct and common bile duct in the long axis (Fig 4).
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Figures 2-5. (2) Recumbent H view of the left portal vein bifurcation. On a subcostal US scan, the left portal vein (p), the ascending branch of the left portal vein (a), and the branches to three segments of the left lobe of the liver (2, 3, and 4) suggest a recumbent H. (3) Recumbent H view of the right portal vein bifurcation. Intercostal oblique US scan shows the branches to the anterior (5 and 8) and posterior (6 and 7) segments of the right lobe of the liver. rpv = right portal vein. (4) Hepatoduodenal ligament view. Sagittal US scan shows the common hepatic duct and common bile duct (CBD) anterior to the main portal vein (MPV). (5) Pancreatic head view. Transverse US scan shows the common bile duct (arrow) along the posterolateral aspect of the pancreatic head. The gastroduodenal artery (arrowhead) courses along the anterolateral aspect of the pancreatic head. PV = portal vein, SV = splenic vein.
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5. Pancreatic head views for assessment of the distal common bile duct. Long-axis and transverse (Fig 5) views of the pancreatic head show the duct along the posterior and lateral aspect of the pancreatic head to the level of the ampulla. To minimize obscuration of the distal common bile duct by overlying bowel gas in the antrum or duodenum, the upright, right posterior oblique position and the partial right and left lateral decubitus positions are used. Graded compression of the bowel loops with a large footprint transducer is also helpful in displacing bowel gas.
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Figures 2-5. (2) Recumbent H view of the left portal vein bifurcation. On a subcostal US scan, the left portal vein (p), the ascending branch of the left portal vein (a), and the branches to three segments of the left lobe of the liver (2, 3, and 4) suggest a recumbent H. (3) Recumbent H view of the right portal vein bifurcation. Intercostal oblique US scan shows the branches to the anterior (5 and 8) and posterior (6 and 7) segments of the right lobe of the liver. rpv = right portal vein. (4) Hepatoduodenal ligament view. Sagittal US scan shows the common hepatic duct and common bile duct (CBD) anterior to the main portal vein (MPV). (5) Pancreatic head view. Transverse US scan shows the common bile duct (arrow) along the posterolateral aspect of the pancreatic head. The gastroduodenal artery (arrowhead) courses along the anterolateral aspect of the pancreatic head. PV = portal vein, SV = splenic vein.
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In the past, US allowed identification of only abnormal intrahepatic bile ducts. With today's modern machines, however, it is possible to see central intrahepatic structures that represent normal bile ducts. These structures are considered normal if they measure 2 mm or less in diameter or not more than 40% of the diameter of the accompanying portal vein (12).
True intrahepatic ductal dilatation is always a significant finding at US, particularly when the "shotgun" ("parallel channel") sign is seen (Fig 6) (13,14). This sign represents a dilated duct in
association with a portal vein branch within a peripheral portal triad. The most sensitive view for detection of dilatation of the intrahepatic bile duct is the subcostal oblique view of the porta hepatis, which shows the right and left hepatic ducts anterior to the portal vein bifurcation. On occasion, the appearance of prominent blood vessels in the liver may be misconstrued as dilated bile ducts at gray-scale US. Color Doppler imaging is often used in these instances to differentiate between the two entities.
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Figure 6. Parallel channel sign of biliary obstruction secondary to cholangiocarcinoma. Sagittal US scan through the right lobe of the liver shows parallel tubes representing a portal vein (pv) and its accompanying dilated bile duct (bd). This US feature is also known as the shotgun sign.
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In contrast, extrahepatic ductal dilatation may be an unimportant US observation. It is a recognized dilemma of US that the size of the common hepatic duct and common bile duct may not accurately reflect the clinical situation. Healthy patients (especially the elderly) and patients who have undergone cholecystectomy may have ductal diameters greater than the threshold level of 6 mm without obstruction. A larger than normal extrahepatic bile duct in a patient without jaundice often represents a normal variant. Furthermore, patients with only intermittent or early obstruction may not have bile duct dilatation at the time of US evaluation (12). In either case, interpretation of the US scan in conjunction with knowledge of the serum alkaline phosphatase level is invaluable.
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US APPEARANCES OF CHOLANGIOCARCINOMA
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Klatskin Tumors
Ductal Dilatation.—Dilatation of the intrahepatic bile ducts is the most frequently seen US abnormality in patients with ductal cholangiocarcinoma. Klatskin tumors classically manifest as segmental dilatation and nonunion of the right and left ducts at the porta hepatis (Fig 7) (4,15–17). These findings may be the first and only clues to the presence of this pathologic condition. Dilated intrahepatic ducts with a normal-caliber extrahepatic duct are also suggestive of Klatskin tumor.
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Figure 7. Infiltrating Klatskin tumor. Subcostal oblique US scan through the porta hepatis shows a soft-tissue mass (m) in the common hepatic duct with invasion of adjacent liver tissue. The invasive component is inferred from the separation of the dilated central bile ducts (bd). pv = portal vein.
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Tumor Characterization.—Characterization of a cholangiocarcinoma requires meticulous evaluation of the point of caliber alteration or ductal occlusion. If the level of obstruction is segmental, this scrutiny should include all the segmental ducts. The papillary and nodular forms of cholangiocarcinoma are relatively easy to see at US. As their name implies, papillary tumors resemble polypoid intraluminal masses (Figs 8, 9). Papillary cholangiocarcinoma is particularly well visualized when associated with a preexisting choledochal cyst (Fig 10). Nodular cholangiocarcinoma manifests as a discrete smooth mass with associated mural thickening. Such tumors may have a shelf of tumoral shouldering (Figs 11, 12). The residual lumen is compromised or obliterated and therefore may appear centrally as an echogenic line (8).\.
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Figures 8, 9. Papillary variant of Klatskin tumor. (8) Sagittal US scan through the common hepatic duct shows an oval, well-defined, soft-tissue intraductal mass filling the lumen and "poking" upward into the right main duct (arrow). (9a) Subcostal oblique US scan through the right (RT) and left (L) hepatic ducts shows nodular intraductal tumor filling both ducts. pv = portal vein. (9b) Endoscopic retrograde cholangiopancreatogram also demonstrates tumoral invasion of both hepatic ducts (arrowheads).
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Figures 8, 9. Papillary variant of Klatskin tumor. (8) Sagittal US scan through the common hepatic duct shows an oval, well-defined, soft-tissue intraductal mass filling the lumen and "poking" upward into the right main duct (arrow). (9a) Subcostal oblique US scan through the right (RT) and left (L) hepatic ducts shows nodular intraductal tumor filling both ducts. pv = portal vein. (9b) Endoscopic retrograde cholangiopancreatogram also demonstrates tumoral invasion of both hepatic ducts (arrowheads).
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Figures 8, 9. Papillary variant of Klatskin tumor. (8) Sagittal US scan through the common hepatic duct shows an oval, well-defined, soft-tissue intraductal mass filling the lumen and "poking" upward into the right main duct (arrow). (9a) Subcostal oblique US scan through the right (RT) and left (L) hepatic ducts shows nodular intraductal tumor filling both ducts. pv = portal vein. (9b) Endoscopic retrograde cholangiopancreatogram also demonstrates tumoral invasion of both hepatic ducts (arrowheads).
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Figure 10a. Cholangiocarcinoma in a preexisting choledochal cyst. (a) Sagittal US scan through the right lobe of the liver shows a soft-tissue mass (M) within a focal sacculation of the common hepatic duct. gb = gallbladder. (b) Coronal magnetic resonance (MR) cholangiopancreatogram helps confirm the presence of the mass (m).
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Figure 10b. Cholangiocarcinoma in a preexisting choledochal cyst. (a) Sagittal US scan through the right lobe of the liver shows a soft-tissue mass (M) within a focal sacculation of the common hepatic duct. gb = gallbladder. (b) Coronal magnetic resonance (MR) cholangiopancreatogram helps confirm the presence of the mass (m).
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Figures 11, 12. Nodular ductal cholangiocarcinoma. (11) Subcostal oblique US scan through the ductal confluence shows diffuse, shelflike thickening of the proximal right hepatic duct (arrowheads). A small residual lumen remains visible. (12) Sagittal (a) and transverse (b) US scans through the common duct show sheetlike thickening of the common hepatic duct (shouldering of tumor [s and arrowheads in a]) with a corresponding "bull's-eye" appearance of the common hepatic duct on the transverse scan (arrows in b). Histopathologic findings helped confirm nodular cholangiocarcinoma. ha = hepatic artery, pv = portal vein.
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Figures 11, 12. Nodular ductal cholangiocarcinoma. (11) Subcostal oblique US scan through the ductal confluence shows diffuse, shelflike thickening of the proximal right hepatic duct (arrowheads). A small residual lumen remains visible. (12) Sagittal (a) and transverse (b) US scans through the common duct show sheetlike thickening of the common hepatic duct (shouldering of tumor [s and arrowheads in a]) with a corresponding "bull's-eye" appearance of the common hepatic duct on the transverse scan (arrows in b). Histopathologic findings helped confirm nodular cholangiocarcinoma. ha = hepatic artery, pv = portal vein.
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Figures 11, 12. Nodular ductal cholangiocarcinoma. (11) Subcostal oblique US scan through the ductal confluence shows diffuse, shelflike thickening of the proximal right hepatic duct (arrowheads). A small residual lumen remains visible. (12) Sagittal (a) and transverse (b) US scans through the common duct show sheetlike thickening of the common hepatic duct (shouldering of tumor [s and arrowheads in a]) with a corresponding "bull's-eye" appearance of the common hepatic duct on the transverse scan (arrows in b). Histopathologic findings helped confirm nodular cholangiocarcinoma. ha = hepatic artery, pv = portal vein.
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Infiltrating cholangiocarcinoma is the most common subtype but is the most difficult to appreciate at US. In some patients, infiltrating cholangiocarcinoma may appear as an obvious central porta hepatis mass. More often, however, isoechoic infiltration of the periductal soft tissue and liver may produce a "mass effect" that may be inferred from the distance that separates the dilated segmental ducts. Subtle alterations in liver echogenicity and pressure effects on adjacent vascular structures, especially the portal vein (Fig 13), may also be helpful. On occasion, focal irregularity of the ducts may be used to suggest the US diagnosis as well as to establish the extent of tumor extension (Fig 14).
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Figure 13a. Subtle Klatskin tumor. (a) Subcostal oblique US scan shows a small segment of dilated right hepatic duct (r) with an adjacent, extremely subtle isoechoic mass (m). The mass is further suggested by compression and bowing of the portal vein (PV) and by the separation of the biliary stent (two echogenic lines) from the anterior edge of the portal vein. (b) Subcostal US scan obtained with slight angulation of the transducer provides optimal visualization of the mass (m), which has slightly increased echogenicity and a hypoechoic rim (arrows). PV = portal vein, r = right hepatic duct.
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Figure 13b. Subtle Klatskin tumor. (a) Subcostal oblique US scan shows a small segment of dilated right hepatic duct (r) with an adjacent, extremely subtle isoechoic mass (m). The mass is further suggested by compression and bowing of the portal vein (PV) and by the separation of the biliary stent (two echogenic lines) from the anterior edge of the portal vein. (b) Subcostal US scan obtained with slight angulation of the transducer provides optimal visualization of the mass (m), which has slightly increased echogenicity and a hypoechoic rim (arrows). PV = portal vein, r = right hepatic duct.
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Figure 14. Mural extension of tumor. Subcostal oblique US scan through the porta hepatis shows an invasive Klatskin tumor with an extensive intraductal lobar component (large arrow). Subtle nodularity along the inferior wall of the left main duct (small arrows) is caused by tumor infiltration.
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Lobar Atrophy.—Although its appearance at computed tomography (CT) is usually obvious, lobar atrophy is often extremely subtle at US and its detection requires extreme vigilance. When lobar atrophy is present, US scans demonstrate crowded, dilated ducts within the atrophic lobe (Fig 15). The dilated ducts will often reach uncustomarily close to the liver surface, which is a clue to the presence of this entity (Fig 16). The associated cholangiocarcinoma is often hilar with dominant involvement of the duct that supplies the involved or atrophic segment. The constellation of these three findings (dilated ducts, ductal crowding, lobar atrophy) is strongly suggestive of cholangiocarcinoma, although long-standing biliary obstruction from surgical trauma or focal biliary obstruction from other causes may produce similar findings. In addition to these features, differences in lobar echogenicity may also reflect either ischemic or fatty changes (Fig 17). In a study by Choi et al (18), lobar atrophy was identified at US in six of 43 patients (14%) with cholangiocarcinoma.\.
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Figure 15a. Lobar atrophy. (a) Subcostal oblique US scan of the liver shows atrophy and ductal crowding of the left lobe. A mass (M) is inferred from the separation of the dilated ducts. (b) Axial CT scan helps confirm the presence of the mass.
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Figure 15b. Lobar atrophy. (a) Subcostal oblique US scan of the liver shows atrophy and ductal crowding of the left lobe. A mass (M) is inferred from the separation of the dilated ducts. (b) Axial CT scan helps confirm the presence of the mass.
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Figure 17a. Geographic alteration in lobar echotexture secondary to a Klatskin tumor. (a) Intercostal oblique US scan through the liver shows marked lobar atrophy of the right lobe (rt). In addition, there is geographic alteration in lobar echotexture, with the right lobe substantially less echogenic than the left lobe (lt). (b) Axial US scan through the left lobe and porta hepatis shows segmentally dilated ducts with nonunion, echotexture variation, and a subtle Klatskin tumor (arrowheads). Segments 2, 3, and 4 are clearly marked.
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Figure 17b. Geographic alteration in lobar echotexture secondary to a Klatskin tumor. (a) Intercostal oblique US scan through the liver shows marked lobar atrophy of the right lobe (rt). In addition, there is geographic alteration in lobar echotexture, with the right lobe substantially less echogenic than the left lobe (lt). (b) Axial US scan through the left lobe and porta hepatis shows segmentally dilated ducts with nonunion, echotexture variation, and a subtle Klatskin tumor (arrowheads). Segments 2, 3, and 4 are clearly marked.
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Staging.—Vascular involvement, lymphadenopathy, and the extent of ductal involvement will all influence the resectability of hilar cholangiocarcinoma. Both vascular involvement and lymphadenopathy are optimally assessed on the subcostal oblique view of the porta hepatis and the scan through the hepatoduodenal ligament.
Vascular involvement in cholangiocarcinoma should be assessed with gray-scale, color Doppler, and spectral Doppler US. The portal vein is more frequently involved and easier to evaluate with US than the smaller hepatic artery. The vessels may be in close proximity to or juxtaposed with the tumor as well as invaded (Fig 18), encased (Fig 19), or obliterated (Fig 20) by the tumor. These findings are often better appreciated at gray-scale US, which provides higher resolution than its color Doppler counterpart. Conversely, a vessel within a tumor may be detected only from its color signal and therefore go undetected at gray-scale US (Figs 21, 22). Proximity to a vessel does not always indicate an unresectable lesion, but this finding should be reported to the referring surgeon. Alteration in the caliber of the vessel with a focal velocity change is suggestive of direct involvement of the vessel wall. Therefore, findings of waveform alterations and velocity increases at spectral Doppler US may allow confirmation of suspicious abnormalities at gray-scale and color Doppler US.
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Figures 18-20. (18) Involvement of the main portal vein. Sagittal gray-scale US scan shows an infiltrative mass in the common bile duct. A nodular component (arrowheads) is seen invading the main portal vein (pv). An indwelling stent is also visible (arrow). (19) Hepatic artery encasement. Subcostal oblique gray-scale US scan through the porta hepatis shows incomplete encasement of the hepatic artery (*) by a mass in the ductal confluence (arrowheads). The hepatic artery is incompletely circumscribed by tumor tissue; there is an intact tissue plane between the artery and the adjacent portal vein (pv). (20) Involvement of the right portal vein. Subcostal oblique gray-scale US scan through the porta hepatis shows an abrupt narrowing (arrow) with complete obliteration of the right portal vein (rpv) secondary to an isoechoic infiltrating Klatskin tumor (m). A biliary stent appears as two parallel echogenic lines within the tumor.
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Figures 18-20. (18) Involvement of the main portal vein. Sagittal gray-scale US scan shows an infiltrative mass in the common bile duct. A nodular component (arrowheads) is seen invading the main portal vein (pv). An indwelling stent is also visible (arrow). (19) Hepatic artery encasement. Subcostal oblique gray-scale US scan through the porta hepatis shows incomplete encasement of the hepatic artery (*) by a mass in the ductal confluence (arrowheads). The hepatic artery is incompletely circumscribed by tumor tissue; there is an intact tissue plane between the artery and the adjacent portal vein (pv). (20) Involvement of the right portal vein. Subcostal oblique gray-scale US scan through the porta hepatis shows an abrupt narrowing (arrow) with complete obliteration of the right portal vein (rpv) secondary to an isoechoic infiltrating Klatskin tumor (m). A biliary stent appears as two parallel echogenic lines within the tumor.
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Figures 18-20. (18) Involvement of the main portal vein. Sagittal gray-scale US scan shows an infiltrative mass in the common bile duct. A nodular component (arrowheads) is seen invading the main portal vein (pv). An indwelling stent is also visible (arrow). (19) Hepatic artery encasement. Subcostal oblique gray-scale US scan through the porta hepatis shows incomplete encasement of the hepatic artery (*) by a mass in the ductal confluence (arrowheads). The hepatic artery is incompletely circumscribed by tumor tissue; there is an intact tissue plane between the artery and the adjacent portal vein (pv). (20) Involvement of the right portal vein. Subcostal oblique gray-scale US scan through the porta hepatis shows an abrupt narrowing (arrow) with complete obliteration of the right portal vein (rpv) secondary to an isoechoic infiltrating Klatskin tumor (m). A biliary stent appears as two parallel echogenic lines within the tumor.
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Figures 21, 22. (21) Left portal vein thrombosis secondary to ductal cholangiocarcinoma. Axial color Doppler US scan through the porta hepatis shows complete thrombosis of the left main and ascending branches (AP) of the portal vein from adjacent tumor invasion. Patent prominent hepatic arterial branches (yellow) run parallel to the thrombosed portal vein. Blue area indicates flow in the main portal vein. No flow is seen in the ascending left portal vein. bd = bile duct. (22) Hepatic artery encasement. Color Doppler US scan through the hepatoduodenal ligaments shows complete encasement of the proximal right lobar branch of the hepatic artery by a tumor mass. ha = hepatic artery, P = portal vein.
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Figures 21, 22. (21) Left portal vein thrombosis secondary to ductal cholangiocarcinoma. Axial color Doppler US scan through the porta hepatis shows complete thrombosis of the left main and ascending branches (AP) of the portal vein from adjacent tumor invasion. Patent prominent hepatic arterial branches (yellow) run parallel to the thrombosed portal vein. Blue area indicates flow in the main portal vein. No flow is seen in the ascending left portal vein. bd = bile duct. (22) Hepatic artery encasement. Color Doppler US scan through the hepatoduodenal ligaments shows complete encasement of the proximal right lobar branch of the hepatic artery by a tumor mass. ha = hepatic artery, P = portal vein.
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Detection of lymphadenopathy in the hepatoduodenal ligaments and the peripancreatic region is sensitive but not specific because not all large nodes may contain tumor tissue and microscopic deposits will be missed with all imaging techniques (19). The morphologic characteristics of nodes are important. A flat node with retention of the echogenic hilar stripe is more often reactive than are nodes that are round and hypoechoic. The occurrence of nodal metastasis alone does not contraindicate surgery because adenectomy of all nodes that are potentially infiltrated by the tumor is routinely performed (6).
Few series have examined US staging versus surgical staging of hilar cholangiocarcinoma (6, 16). These studies showed US to be relatively deficient in important areas such as estimation of tumor spread and determination of tumor resectability. Nevertheless, it is our experience that US is adept in the identification of cholangiocarcinoma and prediction of those tumors that are unresectable.
Extrahepatic Bile Duct Tumors
Tumors that involve the common bile duct differ from their Klatskin counterparts only in the percentage of distribution of the three pathologic subtypes. Carcinomas of the distal common bile duct are usually small and have a better prognosis than the more central Klatskin tumor. A short stricture or, less often, a polypoid mass (Fig 23) is identified. It is sometimes difficult to reliably differentiate this tumor from a pancreatic head or an ampullary tumor at imaging.
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Figure 23. Polypoid mass in the distal common bile duct. Axial US scan through the pancreatic head shows a nodule with frondlike surface excrescences in the distal common bile duct (arrow). PV = portal vein.
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US Pitfalls
Ideally, initial US evaluation of suspected cholangiocarcinoma should be performed before any biliary intervention with stent placement. The reasons for this are threefold. First, to accurately identify the site of tumoral involvement, every dilated duct should be followed to its point of caliber change. Thus, ductal decompression by means of an endoscopic or percutaneous approach makes tumor evaluation more difficult because ductal dilatation may no longer be used to aid in tumor identification. Second, gas artifact from pneumobilia related to stent placement or ampullotomy may obscure tumor. Finally, catheter-related inflammation may cause thickening of the ductal wall, thereby interfering with tumor staging (Fig 24). Although it continues to be our preference to see patients before they undergo biliary decompression, referral patterns and clinical decisions often preclude this arrangement, in which case US scans are more difficult to interpret but are still valuable.
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Figure 24. Mural thickening of the entire common bile duct due to stent placement. Sagittal US scan through the hepatoduodenal ligaments shows a circumferentially thickened common hepatic duct (arrowheads) with preservation of luminal patency. This thickening is difficult to differentiate from a nodular cholangiocarcinoma or cholangitis. A stent is present but is not seen on this view. PV = portal vein.
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Differential Diagnosis of Ductal Carcinoma
The differential diagnosis of ductal cholangiocarcinoma depends on its location and US appearance. In particular, lesions at the ductal confluence may be mimicked by inflammatory cholangitis (acquired immunodeficiency syndrome, sclerosing cholangitis), oriental cholangitis, benign biliary tumors, invasive hepatoma, or gallbladder cancer. Lesions of the distal common bile duct may be mimicked by ampullary or pancreatic cancer, nonshadowing stones, papillomas, adenomas, blood clots, and benign strictures. Tumor tissue that is metastatic to the bile duct or adjacent nodes may simulate cholangiocarcinoma at any level.
Sclerosing Cholangitis and Acquired Immunodeficiency Syndrome.—Sclerosing cholangitis and acquired immunodeficiency syndrome are characterized by fibrotic thickening of the bile ducts and adjacent fibrofatty tissues. They affect the intrahepatic and extrahepatic ducts in the majority of patients and occasionally involve the gallbladder and cystic duct (20).
The US hallmark of sclerosing cholangitis in the common duct is smooth or irregular wall thickening (Fig 25). Multifocal strictures and beading develop in the intrahepatic ducts (20). In some cases, obliteration of the bile ducts occurs. Given the fibrotic nature of sclerosing cholangitis, bile duct dilatation may be completely lacking in a patient with jaundice who is afflicted with this illness.
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Figure 25. Sclerosing cholangitis mimicking nodular ductal cholangiocarcinoma. Sagittal US scan through the hepatoduodenal ligaments shows thickening and nodularity of the common hepatic duct (arrowheads). PV = portal vein.
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Thus, cholangitis and cholangiocarcinoma may have similar imaging characteristics. Furthermore, the risk of development of cholangiocarcinoma is substantial in patients with long-standing cholangitis. The prevalence of cholangiocarcinoma complicating primary sclerosing cholangitis has varied from 4% to 19% (21). Several US features should raise the possibility of malignancy in patients with sclerosing cholangitis, including marked bile duct dilatation above a dominant stricture and a polypoid mass greater than 1 cm in diameter. Progression of strictures with increasing "mass effect" at serial US is also suspicious for malignancy (Fig 26).
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Figure 26a. Ductal cholangiocarcinoma in a patient with preexisting sclerosing cholangitis. (a) Axial US scan through the porta hepatis shows a thick-walled common bile duct (diameter, 2.2 cm) with an indwelling stent. (b) Axial US scan through the porta hepatis obtained 3 months later shows marked enlargement of the common bile duct (diameter, 3.1 cm). Cholangiocarcinoma was proved at histopathologic analysis. Cross-hatch calipers in each image indicate the lateral margins of the duct.
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Figure 26b. Ductal cholangiocarcinoma in a patient with preexisting sclerosing cholangitis. (a) Axial US scan through the porta hepatis shows a thick-walled common bile duct (diameter, 2.2 cm) with an indwelling stent. (b) Axial US scan through the porta hepatis obtained 3 months later shows marked enlargement of the common bile duct (diameter, 3.1 cm). Cholangiocarcinoma was proved at histopathologic analysis. Cross-hatch calipers in each image indicate the lateral margins of the duct.
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Oriental Cholangitis.—Oriental cholangitis is extremely common in Asia but may occur in any patient with biliary stasis. In Asians, this stasis is commonly due to infestation with biliary parasites (Clonorchis [Opisthorchis] sinensis), which in turn leads to biliary deconjugation and precipitation of calcium bilirubinate (soft, mudlike consistency) in the ducts. These deposits are usually multiple and develop in the intrahepatic and extrahepatic bile ducts, often forming a cast of the biliary tree. The lateral left lobe is most commonly affected. At US, the stones have a dramatic range of appearances. They may have a moderate echogenicity and lack acoustic shadowing, thereby mimicking blood, pus, and biliary neoplasm. If there is associated lobar atrophy, differentiation from cholangiocarcinoma may be difficult. Larger stones that cast a shadow make differentiation much more straightforward.
Other Biliary Neoplasms.—Gallbladder cancer with contiguous spread to the bile ducts at the porta hepatis is often indistinguishable from cholangiocarcinoma (Fig 27). Several benign tumors may also mimic cholangiocarcinoma. These include papillary adenomas, granular cell tumor, mesenchymal tumors (rare), and heterotopic gastric mucosa (rare).
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Figure 27a. Invasive gallbladder cancer mimicking a Klatskin tumor. (a) Sagittal US scan through the gallbladder fossa shows a solid mass (m) containing trapped stones. (b) Axial US scan through the porta hepatis shows the tumor (m) extending up to and obstructing the common bile duct (cbd).
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Figure 27b. Invasive gallbladder cancer mimicking a Klatskin tumor. (a) Sagittal US scan through the gallbladder fossa shows a solid mass (m) containing trapped stones. (b) Axial US scan through the porta hepatis shows the tumor (m) extending up to and obstructing the common bile duct (cbd).
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Granular cell tumors are Schwann cell–derived biliary tumors of young black women that produce substantial epithelial hyperplasia, which results in bile duct thickening and stenosis. These tumors often occur at the level of the junction of the common bile duct and common hepatic duct, and their appearance mimics cholangiocarcinoma. They are benign, and simple excision is curative.
Papillary adenomas are the most common benign biliary tumors. At US, they appear as non-shadowing, expansile nodules that fill the bile duct lumen. They are indistinguishable from the papillary variant of cholangiocarcinoma
(Fig 28).
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Figure 28a. Papillary adenoma in a preexisting choledochal cyst. (a) Sagittal US scan through the porta hepatis shows an eccentric mass (m) within a biliary diverticulum. (b) Coronal MR cholangiopancreatogram helps confirm the presence of the mass (m). Cholangiocarcinoma in a choledochal cyst was proved at histopathologic analysis.
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Figure 28b. Papillary adenoma in a preexisting choledochal cyst. (a) Sagittal US scan through the porta hepatis shows an eccentric mass (m) within a biliary diverticulum. (b) Coronal MR cholangiopancreatogram helps confirm the presence of the mass (m). Cholangiocarcinoma in a choledochal cyst was proved at histopathologic analysis.
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Rare malignant tumors such as embryonal rhabdomyosarcoma (pediatric) and lymphoma are occasionally encountered.
Metastatic Tumor.—Metastatic adenopathy to the porta hepatis from primary tumors such as those of the gastrointestinal tract, pancreas, or breast and lymphoma may occasionally mimic hilar cholangiocarcinoma. Their tendency to form extensive lobulated masses that surround rather than fill the bile ducts is usually suggestive of the correct diagnosis. On occasion, a discrete metastasis from the breast or colon (Fig 29) or a melanoma (Fig 30) may be seen as a polypoid intraluminal ductal mass.
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Figures 29, 30. (29) Metastasis mimicking papillary cholangiocarcinoma of the intrahepatic bile duct. Transverse US scan through the left lobe of the liver shows a papillary intraductal mass (arrow) obstructing a segmental bile duct (s). Metastatic rectal cancer was proved at histopathologic analysis. (30) Metastasis mimicking papillary cholangiocarcinoma of the extrahepatic bile duct. Sagittal US scan through the common bile duct (cbd) shows a polypoid intraluminal mass (m) causing bile duct obstruction. Metastatic melanoma was proved at histopathologic analysis.
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Figures 29, 30. (29) Metastasis mimicking papillary cholangiocarcinoma of the intrahepatic bile duct. Transverse US scan through the left lobe of the liver shows a papillary intraductal mass (arrow) obstructing a segmental bile duct (s). Metastatic rectal cancer was proved at histopathologic analysis. (30) Metastasis mimicking papillary cholangiocarcinoma of the extrahepatic bile duct. Sagittal US scan through the common bile duct (cbd) shows a polypoid intraluminal mass (m) causing bile duct obstruction. Metastatic melanoma was proved at histopathologic analysis.
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Mirizzi Syndrome.—Mirizzi syndrome is an uncommon cause of extrahepatic bile duct obstruction due to an impacted stone in the cystic duct that creates extrinsic compression of the common hepatic duct (Fig 31). The inflammatory component of this syndrome may be masslike and suggest cholangiocarcinoma. However, identification of the shadowing from the stone should allow differentiation of these two entities.
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Figure 31a. Mirizzi syndrome mimicking a Klatskin tumor. (a) Sagittal US scan through the porta hepatis shows a large gallstone (S) in the region of the common bile duct and common hepatic duct dilating the latter (cd). GB = gallbladder. (b) Subcostal US scan obtained cephalad to a shows an infiltrative "mass" (arrowheads) obstructing the proximal right and left bile ducts, thereby mimicking a Klatskin tumor. (c) Endoscopic retrograde cholangiopancreatogram helps confirm the diagnosis. Inflammatory tissue was proved at surgery.
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Figure 31b. Mirizzi syndrome mimicking a Klatskin tumor. (a) Sagittal US scan through the porta hepatis shows a large gallstone (S) in the region of the common bile duct and common hepatic duct dilating the latter (cd). GB = gallbladder. (b) Subcostal US scan obtained cephalad to a shows an infiltrative "mass" (arrowheads) obstructing the proximal right and left bile ducts, thereby mimicking a Klatskin tumor. (c) Endoscopic retrograde cholangiopancreatogram helps confirm the diagnosis. Inflammatory tissue was proved at surgery.
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Figure 31c. Mirizzi syndrome mimicking a Klatskin tumor. (a) Sagittal US scan through the porta hepatis shows a large gallstone (S) in the region of the common bile duct and common hepatic duct dilating the latter (cd). GB = gallbladder. (b) Subcostal US scan obtained cephalad to a shows an infiltrative "mass" (arrowheads) obstructing the proximal right and left bile ducts, thereby mimicking a Klatskin tumor. (c) Endoscopic retrograde cholangiopancreatogram helps confirm the diagnosis. Inflammatory tissue was proved at surgery.
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Other Entities.—Biliary stasis secondary to stricture from sclerosing cholangitis may predispose affected patients to bile salt deposition and resultant formation of nonshadowing stones and sludge, which may be virtually indistinguishable from papillary cholangiocarcinoma (Figs 32, 33). These oval or round, avascular intraductal masses often become impacted within the common bile duct, which restricts their mobility. On occasion, hemobilia secondary to liver biopsy or blunt trauma will form a soft-tissue cast within a duct, thereby mimicking intraductal tumor (Fig 34). The patient's recent medical history will usually alert the radiologist to this entity. In liver transplantation centers, biliary necrosis secondary to either ischemia or transplant rejection (Fig 35) may produce an appearance not unlike nodular cholangiocarcinoma and sclerosing cholangitis. The affected bile ducts are often irregularly thickened and beaded. On occasion, a soft-tissue cast of sloughed endothelium is present within the biliary tree. Bile duct injury secondary to laparoscopic cholecystectomy may also manifest as abrupt ductal termination. Patient history and lack of mass effect are usually diagnostic (Fig 36).
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Figure 32a. Common bile duct stone mimicking papillary cholangiocarcinoma. Sagittal (a) and axial (b) US scans through a dilated common bile duct show a round, "polypoid" intraluminal lesion (s). Faint acoustic shadowing is seen in a. A stone was proved at endoscopic retrograde cholangiopancreatography.
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Figure 32b. Common bile duct stone mimicking papillary cholangiocarcinoma. Sagittal (a) and axial (b) US scans through a dilated common bile duct show a round, "polypoid" intraluminal lesion (s). Faint acoustic shadowing is seen in a. A stone was proved at endoscopic retrograde cholangiopancreatography.
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Figures 33-36. (33) Common bile duct stone suggestive of papillary cholangiocarcinoma in a patient with a stricture and long-standing sclerosing cholangitis. Sagittal US scan through the porta hepatis shows a well-defined, nonshadowing, avascular echogenic mass in the extrahepatic bile duct (arrows). Lack of shadowing makes differentiation of the impacted stone from a tumor particularly difficult. (34) Hemobilia mimicking ductal cholangiocarcinoma in a patient who had undergone liver biopsy. Sagittal US scan through the porta hepatis shows an ill-defined, echogenic soft-tissue mass (arrow) filling the dilated extrahepatic bile duct. Blood was extracted at endoscopic retrograde cholangiopancreatography. (35) Bile duct rejection in a liver transplant recipient. Sagittal oblique US scan through the porta hepatis shows diffuse circumferential thickening of the right hepatic ducts with only a small residual central lumen (arrowheads). The patient had undergone transplantation 3 weeks earlier and had demonstrated a sudden elevation in liver enzyme levels. Differential diagnosis included recurrent sclerosing cholangitis, which is highly unusual given the timing of this event. (36) Postoperative stricture mimicking a ductal cholangiocarcinoma. Sagittal US scan through the porta hepatis shows abrupt tapering of a dilated common hepatic duct (arrowhead) secondary to previous laparoscopic gallbladder surgery. No mass is present.
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Figures 33-36. (33) Common bile duct stone suggestive of papillary cholangiocarcinoma in a patient with a stricture and long-standing sclerosing cholangitis. Sagittal US scan through the porta hepatis shows a well-defined, nonshadowing, avascular echogenic mass in the extrahepatic bile duct (arrows). Lack of shadowing makes differentiation of the impacted stone from a tumor particularly difficult. (34) Hemobilia mimicking ductal cholangiocarcinoma in a patient who had undergone liver biopsy. Sagittal US scan through the porta hepatis shows an ill-defined, echogenic soft-tissue mass (arrow) filling the dilated extrahepatic bile duct. Blood was extracted at endoscopic retrograde cholangiopancreatography. (35) Bile duct rejection in a liver transplant recipient. Sagittal oblique US scan through the porta hepatis shows diffuse circumferential thickening of the right hepatic ducts with only a small residual central lumen (arrowheads). The patient had undergone transplantation 3 weeks earlier and had demonstrated a sudden elevation in liver enzyme levels. Differential diagnosis included recurrent sclerosing cholangitis, which is highly unusual given the timing of this event. (36) Postoperative stricture mimicking a ductal cholangiocarcinoma. Sagittal US scan through the porta hepatis shows abrupt tapering of a dilated common hepatic duct (arrowhead) secondary to previous laparoscopic gallbladder surgery. No mass is present.
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Figures 33-36. (33) Common bile duct stone suggestive of papillary cholangiocarcinoma in a patient with a stricture and long-standing sclerosing cholangitis. Sagittal US scan through the porta hepatis shows a well-defined, nonshadowing, avascular echogenic mass in the extrahepatic bile duct (arrows). Lack of shadowing makes differentiation of the impacted stone from a tumor particularly difficult. (34) Hemobilia mimicking ductal cholangiocarcinoma in a patient who had undergone liver biopsy. Sagittal US scan through the porta hepatis shows an ill-defined, echogenic soft-tissue mass (arrow) filling the dilated extrahepatic bile duct. Blood was extracted at endoscopic retrograde cholangiopancreatography. (35) Bile duct rejection in a liver transplant recipient. Sagittal oblique US scan through the porta hepatis shows diffuse circumferential thickening of the right hepatic ducts with only a small residual central lumen (arrowheads). The patient had undergone transplantation 3 weeks earlier and had demonstrated a sudden elevation in liver enzyme levels. Differential diagnosis included recurrent sclerosing cholangitis, which is highly unusual given the timing of this event. (36) Postoperative stricture mimicking a ductal cholangiocarcinoma. Sagittal US scan through the porta hepatis shows abrupt tapering of a dilated common hepatic duct (arrowhead) secondary to previous laparoscopic gallbladder surgery. No mass is present.
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Figures 33-36. (33) Common bile duct stone suggestive of papillary cholangiocarcinoma in a patient with a stricture and long-standing sclerosing cholangitis. Sagittal US scan through the porta hepatis shows a well-defined, nonshadowing, avascular echogenic mass in the extrahepatic bile duct (arrows). Lack of shadowing makes differentiation of the impacted stone from a tumor particularly difficult. (34) Hemobilia mimicking ductal cholangiocarcinoma in a patient who had undergone liver biopsy. Sagittal US scan through the porta hepatis shows an ill-defined, echogenic soft-tissue mass (arrow) filling the dilated extrahepatic bile duct. Blood was extracted at endoscopic retrograde cholangiopancreatography. (35) Bile duct rejection in a liver transplant recipient. Sagittal oblique US scan through the porta hepatis shows diffuse circumferential thickening of the right hepatic ducts with only a small residual central lumen (arrowheads). The patient had undergone transplantation 3 weeks earlier and had demonstrated a sudden elevation in liver enzyme levels. Differential diagnosis included recurrent sclerosing cholangitis, which is highly unusual given the timing of this event. (36) Postoperative stricture mimicking a ductal cholangiocarcinoma. Sagittal US scan through the porta hepatis shows abrupt tapering of a dilated common hepatic duct (arrowhead) secondary to previous laparoscopic gallbladder surgery. No mass is present.
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Peripheral Cholangiocarcinoma
Peripheral cholangiocarcinoma is a rare bile duct malignancy that differs clinically from Klatskin tumors in that the patient does not present with jaundice. This tumor has two distinct US appearances: nodular and infiltrating. The nodular form predominates and appears at US as a solitary mass with a distinct right lobe predilection. The infiltrative form of peripheral cholangiocarcinoma is rare and appears as a diffusely abnormal liver echotexture. Increasing tumor echogenicity together with increasing tumor size is a well-documented finding (22). Tumors less than 3 cm in diameter tend to be hypoechoic relative to liver parenchyma, whereas lesions greater than 3 cm in diameter tend toward hyper-echogenicity. The prevalence of metastasis or extrahepatic extension is high even for peripheral cholangiocarcinoma of relatively small size. In a series by Wibulpolprasert and Dhiensiri (22), almost 91% of peripheral cholangiocarcinomas less than 5 cm in diameter had spread extrahepatically at the time of surgery.
On occasion, a papillary peripheral cholangiocarcinoma produces abundant mucin, resulting in a well-marginated cystic mass. Mucin may result in tumor calcification (Fig 37) and may also obstruct the ductal lumen distal to the carcinoma. Occasionally, abundant mucin fills and distends the bile ducts proximal to a peripheral cholangiocarcinoma.
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Figure 37a. Peripheral cholangiocarcinoma. (a) Axial US scan through the left lobe of the liver (lt) shows a large, poorly defined hepatic mass with diffuse flecks of increased echo-genicity that are suggestive of micro-calcifications. (b) Sagittal US scan shows a massively dilated common bile duct (CBD). (c) CT scan helps confirm the diagnosis. Peripheral cholangiocarcinoma with abundant ductal mucin was proved at histopathologic analysis.
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Figure 37b. Peripheral cholangiocarcinoma. (a) Axial US scan through the left lobe of the liver (lt) shows a large, poorly defined hepatic mass with diffuse flecks of increased echo-genicity that are suggestive of micro-calcifications. (b) Sagittal US scan shows a massively dilated common bile duct (CBD). (c) CT scan helps confirm the diagnosis. Peripheral cholangiocarcinoma with abundant ductal mucin was proved at histopathologic analysis.
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Figure 37c. Peripheral cholangiocarcinoma. (a) Axial US scan through the left lobe of the liver (lt) shows a large, poorly defined hepatic mass with diffuse flecks of increased echo-genicity that are suggestive of micro-calcifications. (b) Sagittal US scan shows a massively dilated common bile duct (CBD). (c) CT scan helps confirm the diagnosis. Peripheral cholangiocarcinoma with abundant ductal mucin was proved at histopathologic analysis.
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Two important US features help differentiate peripheral cholangiocarcinoma from hepatoma. First and foremost, unlike hepatoma, peripheral cholangiocarcinoma does not have a hypoechoic halo at US. A second feature is the dilatation of bile ducts peripheral to the tumor, which was observed in 31% of cases of peripheral cholangiocarcinoma in the series by Wibulpolprasert and Dhiensiri (22) and in only 2% of hepatocellular carcinomas in the series by Lee et al (23).
Metastasis to the liver, particularly from a primary gastrointestinal tumor, may also be associated with biliary intraluminal masses that mimic peripheral cholangiocarcinoma (Fig 38).
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Figure 38. Colon metastasis mimicking peripheral cholangiocarcinoma. Sagittal US scan of the right lobe of the liver shows a large, echogenic mass (m) obstructing the peripheral part of the bile duct. Metastatic colon cancer was proved at histopathologic analysis.
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CONCLUSIONS
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US has been widely accepted as an initial screening procedure for bile duct dilatation in patients with jaundice. A variety of modalities are used to further characterize disease in patients with ductal dilatation are more variable, most notably MR cholangiopancreatography and endoscopic retrograde cholangiopancreatography. We hold a more favorable view of the potential role of US in patients in whom cholangiocarcinoma is ultimately proved. In competent hands, modern high-resolution US equipment with color Doppler imaging capability should allow sensitive detection of this rare tumor. Furthermore, characterization as to tumor type, extent, and potential for resectability is now possible.
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References
|
|---|
-
Perrett RS, Thorson MK, Lawson TL. Neoplastic diseases of the gallbladder and biliary tract. In: Freeny PC, Stevenson GW, eds. Alimentary tract radiology. 5th ed. St Louis, Mo: Mosby–Year Book, 1994; 333-342.
-
Buetow P, Buck J. Tumors of the biliary tract: benign and malignant—AFIP course notes Washington, DC: Armed Forces Institute of Pathology, 1993.
-
Laing F. The gallbladder and bile ducts. In: Rumack C, Wilson S, Charbonneau J, eds. Diagnostic ultrasound. 2nd ed. St Louis, Mo: Mosby–Year Book, 1998; 175-225.
-
Meyer D, Weinstein BJ. Klatskin tumors of the bile ducts: sonographic appearance. Radiology 1983; 148:803-804.[Abstract/Free Full Text]
-
Parulekar S. Gallbladder and bile ducts. In: McGahan JP, Goldberg BB, eds. Diagnostic ultrasound: a logical approach. Philadelphia, Pa: Lippincott-Raven, 1997; 693-755.
-
Neumaier CE, Bertolotto M, Perrone R, Martinoli C, Loria F, Silvestri E. Staging of hilar cholangiocarcinoma with ultrasound. J Clin Ultrasound 1995; 23:173-178.[Medline]
-
Honickman SP, Mueller PR, Wittenberg J, et al. Ultrasound in obstructive jaundice: prospective evaluation of site and cause. Radiology 1983; 147:511-515.[Abstract/Free Full Text]
-
Robledo R, Avertano M, Prieto M. Extrahepatic biliary ductal cancer. Radiology 1996; 198:869-879.[Abstract/Free Full Text]
-
Couinaud C. Le foie: études anatomiques et chirurgicales Paris, France: Masson, 1957.
-
Rumack C, Wilson S, Charbonneau J. Diagnostic ultrasound 2nd ed. Vol 1. St Louis, Mo: Mosby–Year Book, 1998; 91.
-
Lafortune M, Madore F, Patriquin H, Breton G. Segmental anatomy of the liver: a sonographic approach to the Couinaud nomenclature. Radiology 1991; 181:443-448.[Abstract/Free Full Text]
-
Cooperberg P. Ultrasonography of the gallbladder and biliary tract. In: Wilson S, eds. Ultrasound: categorical course syllabus. Leesburg, Va: American Roentgen Ray Society, 1993; 143-149.
-
Weill F, Eisencher A, Zeltner F. Ultrasonic study of the normal and dilated biliary tree: the "shotgun sign". Radiology 1978; 127:221-224.[Abstract]
-
Conrad MR, Landay MJ, Janes JO. Sonographic "parallel channel" sign of biliary tree enlargement in mild to moderate obstructive jaundice. AJR 1978; 130:279-286.[Abstract]
-
Smout JL, Bellemans MA, Van Herreweghe W. Klatskin tumors: radiological and imaging findings in eleven patients. J Belge Radiol 1991; 74:177-181.[Medline]
-
Yeung EY, McCarthy P, Gompertz RH, Benjamin S, Gibson RN, Dawson P. The ultrasonographic appearances of hilar cholangiocarcinoma (Klatskin tumours). Br J Radiol 1988; 61:991-995.[Abstract/Free Full Text]
-
Hann L, Greatrex K, Bach A, Fong Y, Blumgart L. Cholangiocarcinoma at the hepatic hilus: sonographic findings. AJR 1997; 168:985-989.[Abstract/Free Full Text]
-
Choi BI, Lee JH, Han MC, Kim SH, Yi JG, Kim CW. Hilar cholangiocarcinoma: comparative study with sonography and CT. Radiology 1989; 172:689-692.[Abstract/Free Full Text]
-
Looser C, Stain SC, Baer HU, Triller J, Blumgart LH. Staging of hilar cholangiocarcinoma by ultrasound and duplex sonography: a comparison with angiography and operative findings. Br J Radiol 1992; 65:871-877.[Abstract/Free Full Text]
-
Kurtz AB, Middleton WD. Ultrasound: the requisites St Louis, Mo: Mosby–Year Book, 1996; 55-73.
-
Porayko MK, Larusso NF, Wiesner RH. Primary sclerosing cholangitis: a progressive disease?. Semin Liver Dis 1991; 11:18-25.[Medline]
-
Wibulpolprasert B, Dhiensiri T. Peripheral cholangiocarcinoma: sonographic evaluation. J Clin Ultrasound 1992; 20:303-314.[Medline]
-
Lee NW, Wong KP, Siu KF, Wong J. Cholangiography in hepatocellular carcinoma with obstructive jaundice. Clin Radiol 1984; 35:119-123.[Medline]
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H.-X. Xu, M.-D. Lu, G.-J. Liu, X.-Y. Xie, Z.-F. Xu, Y.-L. Zheng, and J.-Y. Liang
Imaging of Peripheral Cholangiocarcinoma With Low-Mechanical Index Contrast-Enhanced Sonography and SonoVue: Initial Experience
J. Ultrasound Med.,
January 1, 2006;
25(1):
23 - 33.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H. J. Kim, A. Y. Kim, S. S. Hong, M.-H. Kim, J. H. Byun, H. J. Won, Y. M. Shin, P. N. Kim, H. K. Ha, and M.-G. Lee
Biliary Ductal Evaluation of Hilar Cholangiocarcinoma: Three-dimensional Direct Multi-Detector Row CT Cholangiographic Findings versus Surgical and Pathologic Results--Feasibility Study
Radiology,
December 1, 2005;
238(1):
300 - 308.
[Abstract]
[Full Text]
[PDF]
|
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K. Khalili, U. Metser, and S. R. Wilson
Hilar Biliary Obstruction: Preliminary Results with Levovist-Enhanced Sonography
Am. J. Roentgenol.,
March 1, 2003;
180(3):
687 - 693.
[Abstract]
[Full Text]
[PDF]
|
|
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|
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J. E. Lopera, J. A. Soto, and F. Munera
Malignant Hilar and Perihilar Biliary Obstruction: Use of MR Cholangiography to Define the Extent of Biliary Ductal Involvement and Plan Percutaneous Interventions
Radiology,
July 1, 2001;
220(1):
90 - 96.
[Abstract]
[Full Text]
[PDF]
|
|
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|
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|
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H. J. V. Braga, K. Imam, and D. A. Bluemke
MR Imaging of Intrahepatic Cholangiocarcinoma: Use of Ferumoxides for Lesion Localization and Extension
Am. J. Roentgenol.,
July 1, 2001;
177(1):
111 - 114.
[Abstract]
[Full Text]
[PDF]
|
|
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|
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D. Ortega, P. N. Burns, D. Hope Simpson, and S. R. Wilson
Tissue Harmonic Imaging: Is It a Benefit for Bile Duct Sonography?
Am. J. Roentgenol.,
March 1, 2001;
176(3):
653 - 659.
[Abstract]
[Full Text]
[PDF]
|
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Top
Abstract
INTRODUCTION
