Bile Duct Cystic Disorders (Choledochochal Cysts)


DEFINITION

A rare malformation of the intra or extrahepatic bile ducts, and possibly leading to cancer if not treated.
'Choledochal cysts' is a misnomer as these lesions usually extend beyond the duct.

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INCIDENCE

Rare.
But notable for high morbidity and mortality
Age
Usually before 16 yrs.
20% in adult life.
Sex
F>M 4:1
Geographic
Much more common in East Asia compared with West.
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AETIOLOGY

Dilation of the intra or extrahepatic bile ducts.

Cause unknown.
- multiple theories proposed:
--> anomalous pancreatobiliary duct jx in many with type I cysts
--> reflux of pancreatic juice; cystic degeneration of duct
- increased ductal pressure is another theory
- abnormal SoO fx implicated in some.
- rare genetic predisposition.

None of these factors explain higher prevalence in Asians living in Asia.
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BIOLOGICAL BEHAVIOUR

Pathophysiology
Cause problems with the flow of bile.
Can lead to cholangitis, pancreatitis, stone formation and jaundice.
May have anomalous connections between the biliary and pancreatic ducts.

Classification
Can be classified according to shape, e.g.
- Fusiform (80%) - spindle tapering at both ends
- Saccular
- Cystic.

Most common classification is Todani modification of Alonso-Lej system:
- 5 types of cystic disorders based on site, shape, extent.
image
Type I
Most common; extrahepatic (50-80%)
- IA = cystic
- IB = focal
- IC = fusiform
II = supraduodenal diverticulum of CHD; rare (2-3%)
III = cystic dilation of intraduodenal CBD (choledochocele) (<10%)
IV = multiple, involving both intra and extra hepatic trees (IVA - 30-40%) or just extrahepatic (IVB <5%)
V (Caroli disease) = only intrahepatic biliary tree; unilobar or bilobar. (<10%)

Complications
Untreated cysts may undergo malignant transformation in up to 2-25%.
- either arising within cyst or elsewhere in the tree.
- risk depends on age: low in children (0.7%) to 3% in 20s, to 75% in elderly.
- wide variety of cancers associated including scc, anaplastic, cholangiosarcoma, hepatoma, adenoCa of pancreas or gallbladder
--> but most common is of course cholangioCa.
- risk greatest for types I, IV, V.
Biliary cirrhosis is a late complication
- may be associated with portal hypertension and its consequences
Rarely present with liver failure (type V) abscess, or rupture / bile peritonitis.
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MANIFESTATIONS

Symptoms

Differs much between children and adults

- children mainly get abdo pain, nausea and vomiting, mild jaundice and abdominal masses
--> classic triad is abdo pain, jaundice and palpable mass only seen in 10-15%; rare in adults
- adults have symptoms mimicking biliary duct disease or pancreatitis
--> may also be an incidental finding on imaging

Local

Symptoms of cholangitis, pancreatitis, choledocholithiasis.
70% also have gallstones, hepatolithiasis or chystolithiasis.

Signs

Palpate

Maybe a lump in children RUQ.
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INVESTIGATIONS

Often found during workup for presumed cholecystitis or pancreatitis.

Bloods
LFTs elevated; jaundice common.
High amylase possible.

Imaging
USS often done first.
CT may provide additional information including.
MRCP increasingly used to define anatomical detail including pancreaticobiliary unions.
PTC may help in type IV cysts and placement of temporary stents as required.
ERCP - must avoid pancreatic duct and may not reach proximal biliary tree

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MANAGEMENT

Surgical
Definitive treatment is complete cyst excision.
- if cyst is left in-situ, there is risk of malignant transformation.
- also relieves biliary obstruction, prevents cholangitis and biliary cirrhosis
- and stops pancreatic reflux
Medically optimize prior to surgery
- treat sepsis / control cholangitis
Severe portal hypertension, liver failure and coagulopathy are contraindications.

Type I disease
Right subcostal excision, exploration for malignancy
Gallbladder resected in routine open fashion.
Common bile duct mobilized, leading to choledochal cyst.
Fully Kocherize duodenum to access posterior duct and pancreas.
Cyst dissected caudally, intrapancreatic portion separated from surrounding tissues.
USS can be used as adjunct to identify anatomy and extent, especially when inflamed.
Duct/cyst transected as distally as possible, avoiding the pancreatic duct.
- may need to open cyst to see it
- cyst then elevated and dissected off the portal vein.
Carefully identify anatomy.
- look at hepatic ducts for strictures
Standard 45-60cm Roux-loop reconstruction for end-side hepaticojejunostomy.
- single layered absorbable suture
Sometimes hazardous due to surrounding inflammation
- beware malignancy, open and excise cyst lining; if difficult, saline injection can facilitate dissection.
- try not to leave any portion of the cyst wall behind.

Type II
Simple cyst excision.
CBD closed either primarily or over a T-tube.
Avoid luminal narrowing; occ. need reconstruction.

Type III: Choledochocele
Low malignant potential
Endscopic sphincterotomy used without excising cyst
In a good candidate, surgical resection possible
- Kockherize, laterl duodenotomy, cannulation of ducts, cyst excision, re-anastomose ducts to duodenum.

Type IV
IVB - complete extrahepatic duct excusion and Roux loop reconstruction.
If unilobar disease in liver, may need hemi-hepatectomy.
Bilobar = complete extrahepatic excision, biliary enteric bypass, drainage of intrahepatic tree with large-bore stents
- can reduce malignant and liver failure risk.

Type V - Caroli Disease
Complicated; biliary stasis, recurrent cholangitis, intrahepatic abscesses; bad.
Preence of absence of hepatic fibrosis, biliary cirrhosis, portal hypertension and extent of intrahepatic cysts dictates management
Hepatectomy if unilobar
Antibiotics, biliary drainage, as for IV
Can consider orthotopic liver transplant in diffuse disease and complications.

Outcomes
Complications include leak, bleeding, wound infx, pancreatitis and fistula.
Late include stricture, cholangitis, hepatolithiasis, cirrhosis, malignancy.
- 25%+, especially with more complex disease e.g. IV
Resection reduces but does not eliminate cholangioCa risk, so all pts need lifelong surveillance

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