Choledochal Cyst

Slide 1 · Choledochal Cyst

Congenital dilatation of the biliary tree

Pathogenesis • morphology • clinicopathologic consequences

Right / left hepatic ducts

Distal bile duct

Schematic morphology; not to scale

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning outcomes

Define choledochal cyst and distinguish extrahepatic from intrahepatic duct disease.

Classify major anatomic patterns and interpret the clinicopathologic consequences.

Relate biliary stasis and epithelial injury to inflammation, stones and cancer risk.

Outline imaging, pathology examination and principles of definitive treatment.

Slide 3 · Normal drainage anatomy: An essential baseline

Right and left hepatic ducts join to form the common hepatic duct.

The cystic duct joins the common hepatic duct to form the common bile duct.

The distal duct traverses the pancreatic region before entering the duodenum.

Cyst location must be described relative to these ductal landmarks.

Right / left hepatic ducts

Distal bile duct

Biliary tree — simplified schematic

Slide 4 · Definition: Congenital abnormal bile duct dilatation

Choledochal cysts as congenital dilatations of the common bile duct.

The term is used clinically for a spectrum of biliary duct cystic malformations.

An important distinction is true ductal communication versus a separate cystic mass.

The defining pathology is abnormal biliary duct architecture, not simply a cystic lesion near the liver.

Right / left hepatic ducts

Distal bile duct

Slide 5 · Why anatomic location determines the diagnosis

Extrahepatic disease involves the common hepatic or common bile duct.

Intraduodenal dilatation has different morphology and treatment considerations.

Intrahepatic duct ectasia suggests Caroli disease or combined involvement.

The extent of involvement predicts risks and influences operative planning.

Duct involvement

Extrahepatic? Intrahepatic?

Intraduodenal? Diverticulum?

Topology guides the type

Slide 6 · Typical age at clinical presentation

Most symptomatic cases present during childhood, often before age 10.

Jaundice and recurrent abdominal pain are characteristic initial complaints.

Approximately 20% become symptomatic only in adulthood (Robbins).

Congenital origin does not require detection during infancy.

Childhood

Delayed adult symptoms

Later complication risk

Slide 7 · Female predominance is a reproducible feature

A female-to-male ratio of approximately 3:1 to 4:1.

The sex distribution helps characterize epidemiology, not establish an individual diagnosis.

Symptoms and imaging remain essential for case identification.

A male patient with typical biliary dilatation can still have the disorder.

Robbins: Female-to-male ratio ≈ 3:1–4:1

Slide 8 · The presenting symptom is often biliary obstruction

Abdominal pain may resemble recurrent biliary colic.

Jaundice indicates impaired handling or drainage of biliary pigments.

Episodes may recur because duct dilatation is a persistent structural abnormality.

Additional symptoms may reflect stones, infection or pancreatitis.

Dilatation

Slow flow

Stones / infection

Slide 9 · Biliary stasis links anatomy to complications

A dilated and poorly draining duct changes the local biliary environment.

Abnormal duct caliber

Relative bile stasis

Inflammation / calculi

Progressive biliary injury

Dilatation is not merely a radiologic observation; It changes biliary physiology.

Slide 10 · Pancreaticobiliary maljunction: Proposed driver

An anomalous pancreaticobiliary junction may permit reciprocal ductal reflux.

Pancreatic juice may enter the bile duct outside normal sphincteric regulation.

Proteolytic pancreatic secretions can injure biliary epithelium.

This model is important but does not account for every cyst subtype.

Abnormal duct junction

Pancreatic juice reflux

Chronic ductal injury

Slide 11 · Proposed pancreatic enzyme injury cascade

Long common channel

Pancreatic reflux

Mucosal inflammation

Wall injury / ectasia

Mechanistic framework: Reflux is a commonly accepted hypothesis, not a universal requirement.

Slide 12 · Pathogenesis is heterogeneous across subtypes

Anomalous duct union is often associated with extrahepatic cystic dilatation.

Developmental duct abnormalities are important for intrahepatic cystic disease.

Some lesions, particularly choledochoceles, may differ in pathogenesis.

An observed cyst does not prove the presence of pancreaticobiliary maljunction.

No single mechanism explains every ductal cyst

Slide 13 · Anatomic forms described directly by Robbins

Segmental or cylindric dilatation of the common bile duct.

Diverticula arising from extrahepatic bile ducts.

Choledochoceles protruding into the duodenal lumen.

Some cases coexist with cystic dilatation of intrahepatic ducts.

Right / left hepatic ducts

Distal bile duct

Slide 14 · Todani classification: A descriptive anatomic framework

Type

Primary distribution

I

Single segmental, cystic or fusiform extrahepatic duct dilatation

II

True extrahepatic biliary diverticulum

III

Intraduodenal terminal duct dilatation: Choledochocele

IV

Multiple duct cysts: IV-A intra- and extrahepatic; IV-B extrahepatic only

V

Segmental intrahepatic duct ectasia (Caroli disease)

Slide 15 · Type I: Isolated extrahepatic duct dilatation

Abnormal enlargement involves the extrahepatic bile duct.

Morphology may be cystic, segmental or fusiform.

The communicating lumen is part of the biliary drainage pathway.

Type I is the dominant anatomic pattern in many clinical series.

Right / left hepatic ducts

Distal bile duct

Slide 16 · Type I subtypes: Morphology within a single group

Type IA: Diffuse cystic dilatation of extrahepatic bile duct.

Type IB: Focal segmental dilatation, often saccular.

Type IC: Diffuse fusiform extrahepatic dilatation.

These are morphology-based subdivisions; Naming conventions should be checked against the classification used locally.

Right / left hepatic ducts

Distal bile duct

Slide 17 · Type II: An extrahepatic bile duct diverticulum

A focal sac protrudes from the wall of an extrahepatic bile duct.

The main duct can remain comparatively normal in caliber.

The diverticular neck may contribute to local stasis.

Distinguish from a noncommunicating adjacent cyst.

Right / left hepatic ducts

Distal bile duct

Slide 18 · Type III: Choledochocele

Cystic enlargement occurs in the distal, intraduodenal duct segment.

The lesion may bulge into the duodenal lumen.

Its relationship to the ampulla and pancreatic duct must be mapped.

Its epithelial lining and malignant potential differ from many large extrahepatic cysts.

Right / left hepatic ducts

Distal bile duct

Slide 19 · Type IV-A: Intrahepatic and extrahepatic involvement

Extrahepatic ductal cystic dilatation coexists with intrahepatic duct ectasia.

Intrahepatic strictures or stasis may persist after extrahepatic reconstruction.

Mapping the distribution of intrahepatic lesions is essential.

Management is individualized to the extent of ductal disease.

Right / left hepatic ducts

Distal bile duct

Slide 20 · Type IV-B: Multiple extrahepatic cysts

More than one extrahepatic bile duct segment is dilated.

Intrahepatic ducts are not part of the defining pattern.

The distinction from IV-A rests on documenting intrahepatic involvement.

Complete anatomic mapping matters more than counting visible sacs alone.

Right / left hepatic ducts

Distal bile duct

Slide 21 · Type V: Caroli disease

Multifocal, segmental cystic dilatation affects larger intrahepatic ducts.

The duct spaces remain continuous with the biliary tree.

Caroli disease under fibropolycystic liver disease.

Its placement in Todani classification does not make all Caroli disease an extrahepatic cyst.

Right / left hepatic ducts

Distal bile duct

Intrahepatic ductal dilatation

Slide 22 · Caroli disease versus Caroli syndrome

Entity

Defining structural association

Caroli disease

Multifocal cystic dilatation of large intrahepatic bile ducts

Caroli syndrome

Caroli-type duct dilatation plus congenital hepatic fibrosis

Congenital hepatic fibrosis

Broad fibrous portal expansions with abnormal bile duct profiles

Choledochal cyst

Typically extrahepatic duct dilatation; May coexist with intrahepatic disease

Slide 23 · Developmental duct plate disease is adjacent context

Ductal plate malformations are a developmental spectrum within fibropolycystic disease.

Persistence of embryonic periportal ductal plates produces abnormal duct architecture.

Caroli syndrome combines intrahepatic duct ectasia and congenital hepatic fibrosis.

Avoid assuming every extrahepatic choledochal cyst is caused by ductal plate malformation.

Prolonged obstruction

Inflammation / injury

Biliary fibrosis

Slide 24 · Three diagnostic questions before assigning a type

Does it communicate with bile ducts?

Which duct level is involved?

Single or multiple regions?

Classify only after demonstrating the complete ductal topology.

Slide 25 · Distinguishing congenital cyst from secondary dilatation

Bile duct cyst

Secondary obstructive duct ectasia

Congenital structural morphology

Duct enlarges because an acquired distal obstruction impedes flow

Usually patterned ductal malformation

Dilation may involve ducts upstream of stone or tumor

Classification describes the lesion itself

Search for the obstructing cause

Can develop secondary stones/strictures

Not every enlarged duct is a choledochal cyst

Slide 26 · Gross pathology: An expanded bile-filled duct

The specimen may show localized or elongated enlargement of an extrahepatic duct.

Wall thickness varies with fibrosis and chronic inflammation.

The lumen may contain bile, sludge or calculi.

Mural nodules or focal thickening merit targeted sampling for dysplasia or carcinoma.

Right / left hepatic ducts

Distal bile duct

Slide 27 · The duct wall may become fibrotic

Expanded ducts can show dense mural collagen with scattered smooth muscle bundles.

Chronic injury and repair contribute to progressive wall remodeling.

Inflammatory infiltrates may be present in the wall.

Severe epithelial injury can leave segments attenuated or denuded.

Biliary epithelium

Inflammatory infiltrate

Fibrotic wall / smooth muscle

Schematic wall layers; Not a micrograph

Slide 28 · Mucosal lining: Not uniformly preserved

Biliary-type columnar epithelium can line extrahepatic duct cysts.

The lining may be flattened, inflamed, hyperplastic or focally lost.

Choledochoceles may have duodenal-type lining in some cases.

Sampling and lesion type affect which changes are identified.

Biliary epithelium

Inflammatory infiltrate

Fibrotic wall / smooth muscle

Schematic wall layers; Not a micrograph

Slide 29 · Histologic chronic inflammation is mechanistically important

Lymphocytic inflammation may accompany fibrotic remodeling.

Superimposed neutrophilic inflammation raises concern for cholangitis.

Reactive atypia can resemble epithelial dysplasia.

Correlate cytology with architectural disorder, inflammation and clinical context.

Biliary epithelium

Inflammatory infiltrate

Fibrotic wall / smooth muscle

Schematic wall layers; Not a micrograph

Slide 30 · Epithelial metaplasia, dysplasia and malignancy

Recurrent inflammation can be associated with epithelial metaplasia.

Dysplasia is a premalignant epithelial alteration requiring careful evaluation.

Invasive adenocarcinoma must be distinguished from reactive atypia.

Robbins explicitly identifies increased adenocarcinoma risk.

Stasis

Chronic injury

Atypia

Potential dysplasia / neoplasia

Slide 31 · Pathology sampling: The entire duct matters

Document cyst extent and relationship to resection margins.

Inspect focally thickened, ulcerated or nodular mucosa.

Sample suspicious regions separately and include representative cyst wall.

Report dysplasia, invasive carcinoma and margin involvement if identified.

Duct involvement

Extrahepatic? Intrahepatic?

Intraduodenal? Diverticulum?

Topology guides the type

Slide 32 · Complication framework: One malformation, several injuries

Abnormal duct

Stones / strictures

Pancreatitis / cholangitis

Hepatic obstruction

Robbins also identifies an elevated risk of adenocarcinoma.

Slide 33 · Bile duct stones form in a stagnant system

Abnormal duct caliber can promote impaired bile clearance.

Biliary sludge and stones may develop in the dilated segments.

Calculi can aggravate obstruction and cause intermittent pain.

Recurrent calculi should trigger investigation for underlying ductal pathology.

Dilatation

Slow flow

Stones / infection

Slide 34 · Stricture produces a second level of obstruction

Luminal narrowing may occur at a duct segment or junction.

A stricture impairs emptying and reinforces bile retention.

Upstream ductal dilatation may worsen with progressive stenosis.

Persistent jaundice or cholangitis warrants attention to fixed narrowing.

Dilatation

Slow flow

Stones / infection

Slide 35 · Ascending cholangitis: An infected obstructed system

Biliary stasis favors infection when bacteria enter the ductal tree.

Typical clinical findings can include fever, right upper quadrant pain and jaundice.

The condition can progress rapidly and requires urgent clinical assessment.

Definitive prevention depends on resolving the obstructive anatomy.

Prolonged obstruction

Inflammation / injury

Biliary fibrosis

Slide 36 · Pancreatitis is a recognized complication

Abnormal distal ductal anatomy may interfere with pancreatic outflow.

Reflux or obstruction may provoke pancreatic inflammation.

Pancreatitis in a child with bile duct dilatation strengthens clinical suspicion.

Pancreatic duct junction anatomy affects imaging and management.

Abnormal duct junction

Pancreatic juice reflux

Chronic ductal injury

Slide 37 · Liver injury from chronic impaired biliary drainage

Chronic large-duct obstruction can produce cholestatic liver injury.

Recurrent cholangitis adds inflammatory parenchymal injury.

Secondary biliary fibrosis may accumulate with prolonged obstruction.

Portal hypertension can emerge in advanced chronic biliary disease.

Prolonged obstruction

Inflammation / injury

Biliary fibrosis

Slide 38 · Adenocarcinoma is the key long-term concern

Choledochal cysts carry a higher risk of biliary adenocarcinoma.

Risk differs by lesion type, age and associated abnormalities.

Malignancy may arise in abnormal ductal epithelium.

Cancer risk is one reason simple internal drainage is inadequate for many cysts.

Stasis

Chronic injury

Atypia

Potential dysplasia / neoplasia

Slide 39 · Do not present one universal cancer-risk percentage

Published risk estimates vary across cohorts and age distributions.

Different studies pool different Todani types and follow-up periods.

Preoperative cancer and metachronous cancer are distinct outcomes.

The robust teaching point is increased risk and continued surveillance.

Stasis

Chronic injury

Atypia

Potential dysplasia / neoplasia

Slide 40 · Infancy: Obstructive manifestations may dominate

An infant may be evaluated for cholestatic jaundice.

A large cystic duct lesion may become evident on ultrasound.

Biliary atresia and other neonatal cholestatic causes remain key differential diagnoses.

Prompt anatomic clarification helps avoid delay in definitive care.

Pattern recognition

Persistent jaundice requires assessment of the entire biliary system.

Slide 41 · Childhood: Recurrent pain and jaundice

Recurrent abdominal pain may be interpreted initially as biliary colic.

Intermittent jaundice may reflect variable obstruction.

Imaging may detect an enlarged communicating extrahepatic duct.

Consider associated stone disease, cholangitis and pancreatitis.

Pattern recognition

Recurrent biliary pain is not specific to gallstones.

Slide 42 · Adulthood: Symptoms can appear after years

About one fifth become symptomatic only in adulthood.

Adults may present with pain, cholangitis, pancreatitis or incidental imaging findings.

Associated stones or strictures may obscure the congenital anomaly.

Adult presentations require specific attention to malignant change.

Childhood

Delayed adult symptoms

Later complication risk

Slide 43 · The classic clinical triad is not a screening rule

The historical triad includes abdominal pain, jaundice and a palpable abdominal mass.

Many affected patients do not have all three findings.

Symptoms may be nonspecific and vary with age or complications.

Absence of a palpable mass does not exclude the diagnosis.

Pattern recognition

Abdominal pain + jaundice + palpable mass

Slide 44 · Laboratory tests describe injury, not anatomy

Bilirubin may rise during clinically significant biliary obstruction.

Cholestatic biochemical abnormalities may accompany impaired drainage.

Inflammatory markers can increase during cholangitis.

No single routine serum assay defines a choledochal cyst type.

Imaging establishes the ductal pattern

Slide 45 · Ultrasonography: First-line structural assessment

Ultrasound can detect a cystic lesion near the hepatic hilum or extrahepatic duct.

Continuity with the biliary tree is an important observation.

Assess intrahepatic duct dilatation and associated gallbladder findings.

Incomplete visualization warrants more comprehensive ductal imaging.

Ultrasound

MRCP

Classify anatomy

Clinical correlation + HPB assessment

Slide 46 · MRCP: Map the entire biliary tree

Magnetic resonance cholangiopancreatography delineates fluid-filled ducts.

It helps characterize extrahepatic and intrahepatic disease distribution.

The distal duct, ampullary region and pancreaticobiliary junction should be assessed.

Noninvasive anatomic mapping helps guide surgical planning.

Duct involvement

Extrahepatic? Intrahepatic?

Intraduodenal? Diverticulum?

Topology guides the type

Slide 47 · CT and ERCP have selective complementary roles

Cross-sectional imaging may help evaluate mass lesions or complications.

ERCP can provide ductal detail and therapeutic access when indicated.

ERCP is invasive and carries complications, including pancreatitis.

Use each modality for a defined diagnostic or therapeutic question.

Ultrasound

MRCP

Classify anatomy

Clinical correlation + HPB assessment

Slide 48 · A complete radiology report should describe topology

Report element

Reason it matters

Exact dilated duct segments

Determines whether disease is extrahepatic or intrahepatic

Cystic / fusiform / diverticular

Supports morphological classification

Distal duct and pancreatic junction

Assesses relevant anomalous anatomy

Stones, stenosis, filling defects

Identifies complications or suspicious obstruction

Intrahepatic involvement

Changes operative planning and surveillance

Slide 49 · Diagnostic synthesis: Structural recognition first

Symptoms raise suspicion; Duct anatomy establishes the lesion.

Clinical / laboratory clues

Ultrasound

MRCP mapping

Subtype + complication review

Escalate to an experienced hepatobiliary team when complex anatomy is identified.

Slide 50 · Differential diagnosis: Pediatric jaundice

Consideration

Discriminating question

Choledochal cyst

Is there congenital cystic dilatation communicating with ducts?

Biliary atresia

Are extrahepatic drainage pathways obliterated or absent?

Obstructing calculus

Is there a focal intraluminal stone and upstream ectasia?

Congenital hepatic fibrosis / Caroli

Are intrahepatic duct and portal fibrosis patterns dominant?

Slide 51 · Differential diagnosis: Cyst near the bile duct

Cystic lesion

Distinguishing feature

Choledochal cyst

Cyst communicates with biliary ductal system

Simple hepatic cyst

No ductal communication

Pancreatic pseudocyst

Pancreatic origin or relevant pancreatitis history

Duodenal duplication cyst

Intestinal wall relation and no typical bile-duct origin

Slide 52 · Management is dictated by cyst class and extent

Anatomy, symptoms, complications and cancer risk determine treatment.

Types I and IV usually require excision of abnormal extrahepatic duct.

Restoration of physiologic bile drainage is part of definitive reconstruction.

Complex intrahepatic disease requires individualized hepatobiliary assessment.

Excise abnormal duct

Re-establish bile drainage

Long-term follow-up

Slide 53 · Type I: Complete excision and reconstruction

Excision aims to remove at-risk abnormal extrahepatic biliary mucosa.

Reconstruction commonly uses Roux-en-Y hepaticojejunostomy.

Associated gallbladder removal is often part of standard excision.

Residual strictures or duct abnormalities must be considered in surgical planning.

Excise abnormal duct

Re-establish bile drainage

Long-term follow-up

Slide 54 · Type II / III: Treatment differs by anatomy

Type II diverticula may be treated by excision of the diverticular lesion.

Type III choledochoceles may be considered for endoscopic therapy in suitable cases.

The presence of dysplasia, obstruction or complex ductal anatomy alters choices.

Management recommendations should be individualized by the treating team.

Duct involvement

Extrahepatic? Intrahepatic?

Intraduodenal? Diverticulum?

Topology guides the type

Slide 55 · Type IV / V: Address intrahepatic disease burden

Type IV-A disease requires evaluation of both intra- and extrahepatic ducts.

Persistent intrahepatic strictures and stones may require further intervention.

Localized Caroli disease may be approached differently from diffuse involvement.

Selected severe cases may require major hepatic surgery or transplantation.

Right / left hepatic ducts

Distal bile duct

Slide 56 · Why internal drainage alone is inadequate

Drain cyst without removal

Abnormal lining persists

Stasis / inflammation may recur

Malignancy risk remains

Complete excision is preferred for lesions with substantial malignancy risk.

Slide 57 · After surgery: Early and late complications differ

Early complications relate to surgery and biliary reconstruction.

Anastomotic strictures may later impair drainage.

Recurrent cholangitis or intrahepatic stones can develop.

Cancer risk may remain elevated despite complete excision.

Excise abnormal duct

Re-establish bile drainage

Long-term follow-up

Slide 58 · Long-term follow-up is an active safety measure

Assess patients for recurrent pain, jaundice, fever and biochemical cholestasis.

Follow-up imaging may be required to evaluate strictures or stones.

Surveillance is particularly important after type I and IV disease.

Exact intervals should follow specialist guidance and patient-specific risk.

Childhood

Delayed adult symptoms

Later complication risk

Slide 59 · Case 1: Childhood recurrent jaundice

An 8-year-old has intermittent abdominal pain and jaundice.

Ultrasound: Smooth cystic enlargement of the extrahepatic bile duct.

Intrahepatic ducts appear comparatively normal.

No obstructing stone is demonstrated.

Question: Which structural category is most likely?

Pattern recognition

Identify the involved duct before naming the subtype.

Slide 60 · Case 1: Interpretation and next step

An isolated extrahepatic cystic lesion supports a type I pattern.

MRCP can define proximal extent and distal duct anatomy.

Assess for pancreaticobiliary maljunction and associated complications.

Specialist evaluation is appropriate because definitive excision is usually advised.

Right / left hepatic ducts

Distal bile duct

Slide 61 · Case 2: Pain, infection and intrahepatic duct ectasia

An adult with recurrent cholangitis has extrahepatic and intrahepatic dilated ducts.

MRCP: Enlarged extrahepatic duct plus multifocal intrahepatic duct ectasia.

Several intrahepatic segments contain stones.

Question: What anatomic category fits best?

Which residual disease could persist after extrahepatic surgery?

Pattern recognition

Account for both extrahepatic and intrahepatic disease.

Slide 62 · Case 2: Interpretation and prognostic issue

The combined distribution supports Todani type IV-A disease.

Intrahepatic stones and strictures may cause recurrent cholangitis.

Planning must consider which ducts can be safely resected or drained.

Surveillance remains necessary after extrahepatic reconstruction.

Right / left hepatic ducts

Distal bile duct

Slide 63 · Common errors in clinical-pathology reasoning

Pitfall

Correction

Every cyst near liver = choledochal cyst

Demonstrate communication with biliary ducts

All cysts arise from a single reflux mechanism

Different forms have heterogeneous pathogenesis

Normal adult history excludes congenital disease

Symptoms can first develop in adulthood

Excision removes all future risk

Residual intrahepatic disease and malignancy risk may remain

All types need identical surgery

Type-specific anatomy dictates treatment

Slide 64 · Integrated clinicopathologic synthesis

Congenital anatomy is the root condition; Complications arise through time.

Bile duct malformation

Altered bile flow

Stones / stricture / infection

Pancreatic and hepatic injury

Epithelial injury creates an additional, long-term adenocarcinoma concern.

Slide 65 · Five facts to retain

Choledochal cysts are congenital ductal dilatations; Many become symptomatic in childhood.

The location and number of affected duct segments determine the anatomic type.

Biliary stasis explains stones, strictures, inflammation and obstruction.

Risk of adenocarcinoma affects the rationale for complete resection.

MRCP-based anatomic mapping and long-term clinical follow-up are central.

Slide 66 · References and source boundaries

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. 2026; ch. 18, p. 782 (primary source).

Adjacent Robbins section: Fibropolycystic Disease, pp. 782–783 (Caroli and ductal plate context).

Brown ZJ et al. Diagnosis and management of choledochal cysts. HPB. 2023;25:14–25.

Soares KC et al. Choledochal Cysts: Presentation, Clinical Differentiation, and Management. J Am Coll Surg. 2014;219:1167–1180.

ACG Clinical Guideline: Focal Liver Lesions. Am J Gastroenterol. 2024 (supplementary practice context).