Biliary pathologies

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Biliary pathologies By Navdeep Singh

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Biliary pathologies

Transcript of Biliary pathologies

Page 1: Biliary pathologies

Biliary pathologies

By Navdeep Singh

Page 2: Biliary pathologies

• Typical pattern of intrahepatic biliary branching. Segments are numbered according to the system of Couinaud. CHD = common hepatic duct, RHD = right hepatic duct, LHD = left hepatic duct, RPSD = right posterior sectoral duct, RASD = right anterior sectoral duct.

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• Variations of biliary branching patterns. The more common are A, B and C.

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• Biliary duct anatomy. CT-IVC (surface rendered maximum intensity reformat) shows trifurcation at the biliary confluence and segments numbered according to Couinaud. Arrowhead shows right anterior sectoral duct; arrow shows right posterior sectoral duct.

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• Luschka describe an intrahepatic duct running adjacent to the gallbladder fossa, unaccompanied by a portal vein branch, and emptying into either the right hepatic or common hepatic duct.

• The term ‘cystohepatic duct’is probably best reserved for small ducts that drain directly into the gallbladder or cystic duct. The significance of these variants is their proximity to the gallbladder and the potential for injury at cholecystectomy resulting in a bile leak.

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GALLBLADDER ANATOMICAL VARIANTS

• Agenesis of the gallbladder is extremely rare, with a prevalence of 0.03–0.07 per cent.

• Double gallbladder occurs in about 0.03 per cent, usually with a shared cystic duct, and the accessory gallbladder is often diseased.

• True gallbladder septae are uncommon and when occurring at the fundus form a Phrygian cap. Frequently, an apparent septum is merely gallbladder wall folding, which can vary with patient position.

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GALLBLADDER STONES

• Prevalence in adults in western community 15 per cent.

• Asymptomatic in about 80 %.

• They confer small lifetime risk of developing gallbladder carcinoma.

• About 70 per cent of gallbladder stones are solely or predominantly cholesterol in type, with up to 30 per cent being black pigment stones composed mainly of calcium bilirubinate.

• 20% radioopaque.

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• US - echogenic foci producing acoustic shadows. Stone mobility is frequently identifiable.

• The sensitivity of US is greater than 95 %. • False-negative diagnoses are usually due to small

stones in patients in whom there is poor acoustic access to the gallbladder because of obesity or other unfavourable anatomy.

• False-negative diagnoses are reduced by careful US technique including the use of tissue harmonic imaging, and a variety of US probe and patient positions.

• Small stones are differentiated from small polyps by the demonstration of mobility or the presence of an acoustic shadow.

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• US shows multiple small shadowing stones. A normal fold lies near the gallbladder neck

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• Gallbladder filled with stones producing the ‘double-arc’ sign; hypoechoicline between two echogenic lines (arrow).

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• Sludge is commonly seen on US, in which it appears as fine, nonshadowing dependent echoes.

• It is composed of calcium bilirubinate granules, cholesterol crystals and glycoproteins.

• It is more commonly seen in chronic fasting states, critically ill patients, those receiving total parenteral nutrition or ceftriaxone and in pregnancy.

• Sludge resolves spontaneously in 50 per cent of patients and gallstones will develop in 5–15 per cent.

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• Milk of calcium bile, or limey bile, is an uncommon condition in which the gallbladder bile becomes very viscous, probably as a result of stasis, and contains a high concentration of calcium bilirubinate.

• On US it causes diffuse echoes, similar to sludge, but is more echogenic with a tendency to layer out and produce an acoustic shadow.

• On CT and, occasionally, on plain radiographs it is visible as layering high-density material.

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• Milk of calcium bile producing fine echoes with a dependent layer that shadows.

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CHOLECYSTITIS• 90–95 % of cases, is due to gallstones (acute calculous

cholecystitis). • The positive predictive values of stones combined with

either tenderness localized to the gallbladder (positive sonographic Murphy's sign), or the presence of a gallbladder wall thickness of >3 mm, are 92 per cent and 95 per cent, respectively.

• Gallstone(s) may be impacted in the neck of the gallbladder and this region must be carefully examined.

• Other US signs are gallbladder distension (diameter >5 cm), pericholecystic fluid, gallbladder wall striations and, occasionally, obvious wall hyperaemia on Doppler examination.

• Fine echoes seen within the gallbladder may be seen due to sludge or pus (gallbladder empyema).

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• Acute cholecystitis. The gallbladder contains small stones in the neck (Nos.1–4) and its wall shows oedematous thickening (5 mm thickness).

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• CT is less accurate than US for acute cholecystitis.

• The CT findings in acute cholecystitis include gallbladder wall thickening, subserosaloedema, gallbladder distension, high-density bile, pericholecystic fluid and inflammatory stranding in the pericholecystic fat.

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• Acute cholecystitison CT. The gallbladder wall is thickened with oedema in the adjacent fat. There is no abnormal contrast enhancement in this case.

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• Gangrenous cholecystitis

• irregularity or asymmetrical thickening of the gallbladder wall, internal membranous echoes resulting from sloughed mucosa and pericholecystic fluid.

• The clinical findings, paradoxically, may diminish with progression to gangrenous change.

• CT signs that suggest gangrenous cholecystitisare gas in the wall or lumen, discontinuous and/or irregular mucosal enhancement, internal membranes representing sloughed mucosa and pericholecystic abscess

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• Acute cholecystitis with localized perforation on (A) US and (B) CT. The thickened gallbladder wall shows a local defect (arrow) and on CT there is small amount of intraperitoneal fluid and oedema of adjacent fat.

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• Emphysematous cholecystitis• Accounts for only 1 %, but has a relatively high

mortality rate. • It is more common in men.• Diabetics, and stones are present.• Diagnosis - intramural and/or intraluminal gas

caused by gas-forming organisms. On US intramural gas appears as focal or diffuse bright echogenic lines. Intraluminal gas, in the nondependent portion of the gallbladder, causes a curvilinear, brightly echogenic band with shadowing, which can make recognition of the gallbladder difficult and lead to a false-negative US result.

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• Emphysematous cholecystitis. Image showing intramural (arrow) as well as intraluminalgallbladder gas.

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• Acalculous cholecystitis

• Usually seen in critically ill patirnts.

• US signs are gallbladder distension, gallbladder wall thickening, echogenic contents and, occasionally, sloughed membranes/mucosa and pericholecystic fluid.

• A positive diagnosis is often difficult as sludge and gallbladder distension may occur without cholecystitis in this group of patients.

• Biliary scintigraphy is possibly the most accurate modality.

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• Chronic acalculous cholecystitis is a controversial entity as there are no clear clinical, pathological or imaging criteria for its diagnosis.

• US may show gallbladder wall thickening and, by definition, no stones.

• Cholescintigraphy followed by the IV infusion of cholecystokinin (CCK), or one of its analogues, can be used to assess gallbladder contractibility.

• An ejection fraction greater than 35 per cent on CCK-cholescintigraphy is generally taken to be an indicator of gallbladder dysfunction and helps select patients who may benefit from cholecystectomy.

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• GALLBLADDER POLYPS

• Majority of polyps are cholesterol and less often adenomatous.

• Cholesterol polyps are usually 2–10 mm in size whereas adenomas can be up to 2 cm.

• Cholesterol polyps are multiple and not often associated with stones whereas adenomas tend to be solitary and associated with stones.

• Appear as small echogenic nonshadowing foci adherent to the gallbladder wall, often in a nondependent portion.

• Polyps per se are usually of no significance, though a diameter of >10 mm or local disruption of the adjacent gallbladder wall suggests malignancy.

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• Gallbladder polyps. (A) Solitary, nondependent and nonshadowing polyp (arrow). (B) Multiple, nonshadowing cholesterol polyps.

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• GALLBLADDER CARCINOMA • Uncommon malignancy that has a very poor prognosis.• presents at a late stage in the sixth and seventh decades

with right upper-quadrant pain, often presenting as hilarbiliary obstruction.

• On imaging as focal or diffuse irregular thickening of the gallbladder wall or as a larger mass in the gallbladder fossawith little or no gallbladder lumen identifiable. Gallbladder stones may appear to be ‘buried’ in the mass.

• Spread to lymph nodes around the portal vein relatively early in its course and at presentation there may be nodal masses extending down to the head of the pancreas.

• spreads to the adjacent liver (segments 4 and 5). • D/D includes Mirizzi syndrome and metastases to the

gallbladder, which are uncommon but include melanoma

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• Gallbladder carcinoma. (A) Polyp with breach of continuity of the underlying wall (arrow). (B) Advanced carcinoma extending outside the fundus, with a nodal metastasis posterior to the pancreatic head (arrow). An associated stone can be seen in the gallbladder neck.

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ROLE OF RADIOLOGY IN INVESTIGATION OF JAUNDICE

• The questions that need to be addressed are:

• 1 Is bile duct obstruction present?

• 2 What is the anatomical level of obstruction?

• 3 What is the cause of the obstruction?

• 4 If the obstruction appears to be malignant:

• a There evidence of nonresectability?

• b In those patients with malignant hilar obstructionwho are unsuitable for surgical resection, what approach should be taken to palliative stenting?

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• Modified Bismuth classification of malignant hilarbiliary obstruction based on proximal extent of tumour.

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• CHOLEDOCHOLITHIASIS

• 90 % of bile duct stones are secondary stones.

• USG - Most commonly used initial imaging modality. Reports of its sensitivity vary greatly with the upper range being 50–80 per cent. The sensitivity in jaundiced patients tends to be better.

• Positive stone diagnosis depends on the demonstration of an intraductal echogenic focus in both the longitudinal and transverse planes.

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• Choledocholithiasis. Small shadowing stone (arrow) in dilated bile duct.

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• Choledocholithiasis. A distal common bile duct stone (arrow) is slightly dense compared with the surrounding low-density bile.

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• Choledocholithiasis. CT-IVC shows a small stone within the opacified distal common bile duct.

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• Choledocholithiasis. Single common duct stone (arrow) on thick-section, oblique, coronal MRCP.

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• ERCP shows a post-cholecystectomystricture (arrow) which, characteristically, is very short.

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• Primary sclerosing cholangitis• 70 % of patients having a background of chronic inflammatory

bowel disease, usually ulcerative colitis.• Characterized on cholangiography by multiple segments of

stricturing involving intrahepatic and/or extrahepatic ducts. A characteristic feature in the common duct is diverticula-like out-pouchings.

• On USG, PSC is characterized by bile duct wall thickening which is most pronounced at sites of stricturing, and the diverticula-like out-pouchings may be seen as local echogenic foci in the duct wall.

• Well-established PSC is associated with areas of atrophy and hypertrophy within the liver, best seen with CT or MRI.

• Bile duct stones occur in about 10 %.• Cholangiocarcinoma occurs in about 10 % and is notoriously difficult

to diagnose early. It should be suspected if there is progressive duct dilatation proximal to a stricture, or if a nodule >1 cm in diameter is identified.

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• Primary sclerosing cholangitis. CT-IVC (maximum intensity, oblique coronal reformat) shows multiple intrahepatic and extrahepatic segments of stricturing.

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• Primary sclerosing cholangitis. Typical bile duct wall thickening on US (arrows).

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• Mirizzi syndrome • is characterized by narrowing of the common duct

caused by inflammation and fibrosis related to chronic gallstone disease.

• Typically a stone is impacted in the neck of the gallbladder, the cystic duct, or cystic duct remnant. A fistula may develop between the gallbladder or cystic duct and the common duct and the stone may partially or totally pass into the common duct.

• The level of stricturing varies, being most common in the upper and middle common duct.

• On cholangiography the stricture is usually smooth, 2–3 cm in length, and often has a concavity toward the right.

• USG - there is ductal dilatation down to the level of a stone that is not clearly within the common duct.

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• Mirizzi syndrome. MRCP (A) shows a stricture of the lower common duct caused by a stone (arrow) lying in an expanded cystic duct on ERCP (B). Multiple gallbladder stones are also seen.

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• Recurrent pyogenic cholangitis• also referred to as oriental cholangiohepatitis, occurs

mainly in South-East Asia or its emigrants.• Characterized by recurrent episodes of cholangitis, bile

duct stones, biliary dilatation and strictures.• Infection is due to enteric bacteria that are thought to be

responsible for stone formation, although parasites, in particular Clonorchis sinensis, may play a partial role.

• The stones are more often intrahepatic, can be very extensive, and are composed of calcium bilirubinate, often visible on CT as high densities within dilated intrahepaticducts.

• US shows duct dilatation and stones that may not shadow. • Cholangiography by any technique shows duct dilatation

and multiple stones, which may be widespread or segmental, and duct strictures are common.

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• Recurrent pyogeniccholangitis. Multiple high-density stones lie in dilated ducts within an atrophic left lobe.

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• CHOLANGIOCARCINOMA • Arises from the bile duct epithelium and that tends to

spread by local infiltration.• Approximately 60 per cent arise in the perihilar region

(Klatskin tumours), less than 30 per cent arise in the distal common duct, and less than 10 per cent are diffuse or multifocal.

• Present as malignant hilar biliary obstruction. • Their appearance on imaging varies with size and

pathological type. Most of the exophytic tumours are less than 5 cm and the infiltrating stenotic tumors are usually less than 1–2 cm in diameter.

• On US the tumours appear as nodules or focal bile duct wall thickening, which are usually slightly hyperechoic.

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• On CT the nodules are usually isodense or slightly hypodense compared with liver and are more easily seen on dual-phase contrast-enhanced imaging;

• the infiltrating stenotic type tend to enhance in the arterial phase and the exophytic are more conspicuous on portal phase contrast-enhanced imaging, where they appear less dense than liver. Delayed phase imaging to 10–20 min may show late tumour enhancement.

• On MRI the tumours are hypointense on T1 and hyperintense on T2 and show some progressive enhancement on dynamic imaging.

• The proximal extent of the stricturing, which critically affects treatment options, is well shown with MRCP, which performs better than US and CT and is comparable to direct cholangiography .

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• Small hilarcholangiocarcinoma(arrowhead) producing obstruction of the right posterior sectoral duct (short arrow), right anterior sectoral duct (long arrow) and left hepatic duct. (A) Thick section oblique coronal MRCP. (B) Axial portal phase CT. (C) Longitudinal US. (D) Transverse colour Doppler US (open arrow: normal left portal vein).

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• Carcinoma of the pancreas. PTC shows a distal common duct stricture that is tight and is shouldered proximally

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Figure 36.38 Carcinoma of the pancreas. ERCP shows adjacent strictures (arrows) of the common bile duct and pancreatic duct (‘double duct sign’).