Cholangiocarcinoma

• Adenocarcinoma of intrahepatic bile duct accounts for 5–20% of primary liver malignancy ^[3]
• Mostly occurs in patients > 50 years ^[3]
• Overall incidence is increasing worldwide, driven particularly by rising intrahepatic cholangiocarcinoma (iCCA) — thought to relate to metabolic risk factors (obesity, NAFLD, diabetes) and improved imaging/diagnosis ^[4]
• Perihilar CCA remains the most common subtype (~50–60%), followed by distal extrahepatic (~20–30%), then intrahepatic (~10–20%) ^[1][2]
• Geographic variation is striking:
  • Southeast Asia (Thailand, especially Isan region): highest worldwide incidence due to endemic liver fluke (Opisthorchis viverrini) infection — incidence can be 85 per 100,000
  • East Asia (including Hong Kong, China, Korea): elevated risk due to Clonorchis sinensis infection and recurrent pyogenic cholangitis (RPC)
  • Western countries: PSC is the dominant risk factor; overall incidence lower (~1–2 per 100,000)

• Association with recurrent pyogenic cholangitis (common in Orientals) ^[3]
• Hepatitis B is endemic in Hong Kong — chronic HBV contributes to both HCC and iCCA
• Hepatolithiasis and RPC ("Hong Kong disease") are important local risk factors ^[5]
• PSC-associated CCA is common in Westerners but relatively uncommon in Hong Kong ^[3]

• Slight male predominance overall (M:F ≈ 1.2–1.5:1) for extrahepatic CCA
• Intrahepatic CCA has roughly equal sex distribution
• Increasing incidence with age; peak incidence in the 7th–8th decade ^[2]

Key anatomical landmarks for classification:

• Intrahepatic cholangiocarcinoma originates from: ^[2]
  • Small intrahepatic ducts (peripheral cholangiocarcinoma) — these form a mass lesion within the liver parenchyma, behaving more like a liver mass
  • Large intrahepatic ducts proximal to the bifurcation of left and right intrahepatic ducts — these behave more like perihilar tumours

• Divided into perihilar and distal segments with the transition occurring at the point where the CBD lies posterior to the duodenum, distal to the insertion of the cystic duct into the CBD ^[2]

• The bile ducts receive their blood supply from the hepatic arterial system (peribiliary vascular plexus), NOT the portal vein. This is important because:
  • CCA tends to cause ischaemic-type strictures as it invades the arterial plexus
  • Hepatic artery involvement is a key determinant of resectability
• Lymphatic drainage follows the hepatoduodenal ligament → coeliac, periportal, and para-aortic lymph nodes
• Common mode of spread includes lymphatic spread ^[2]

• The biliary tree has extensive perineural networks within the hepatoduodenal ligament
• This explains why CCA has a notorious tendency for perineural invasion (tumour spreads along nerve sheaths) — one of its hallmark histological features ^[2]

Cholangiocytes are not passive conduits. They:

• Modify bile composition (secrete bicarbonate, chloride; absorb water, glucose, amino acids)
• Participate in the cholehepatic shunt for bile salt recycling
• Express various receptors and growth factors that, when dysregulated, can promote carcinogenesis

The carcinogenesis of CCA follows a multi-step model, similar to the adenoma–carcinoma sequence in colorectal cancer but occurring in cholangiocytes:

Normal cholangiocyte → Hyperplasia → Dysplasia → Carcinoma in situ → Invasive carcinoma

Key molecular pathways:

1. Chronic inflammation → NF-κB activation → COX-2 upregulation → prostaglandin-mediated cell proliferation and inhibition of apoptosis
2. IL-6/STAT3 pathway — IL-6 released by inflammatory cells activates STAT3 in cholangiocytes → promotes survival and proliferation
3. Bile acid toxicity — hydrophobic bile acids cause oxidative DNA damage and activate EGFR/MAPK signalling
4. Growth factor dysregulation — overexpression of VEGF, PDGF, HGF → angiogenesis and tumour growth
5. Tumour suppressor loss — p53 mutations (especially in Thorotrast-related CCA), p16/CDKN2A silencing, SMAD4 loss
6. Oncogenic mutations — IDH1/IDH2 mutations (especially in iCCA, ~15–20%), FGFR2 fusions (iCCA, ~15%), KRAS mutations (extrahepatic CCA)

Majority of cholangiocarcinoma (> 90%) are adenocarcinoma ^[2]

Cholangiocarcinoma is characterized by: ^[2]

• Slow growth
• High rate of local invasion
• Mucin production
• Tendency to invade perineural sheath and spread along nerves (perineural invasion is a hallmark and explains why margins are often positive even after seemingly complete resection)

Adenocarcinoma is further divided into 3 types: ^[2]

Why does the sclerosing type have such dense fibrosis? Because the tumour cells secrete TGF-β and PDGF, which activate surrounding stromal fibroblasts (cancer-associated fibroblasts) to produce collagen. This desmoplastic reaction actually creates a protective microenvironment for the tumour and makes it resistant to chemotherapy penetration.

Particularly for iCCA, the WHO recognizes:

• Mass-forming — a discrete intrahepatic mass (most common pattern for iCCA)
• Periductal-infiltrating — tumour grows along bile duct walls causing strictures without a discrete mass
• Intraductal-growing — papillary growth within the bile duct lumen (best prognosis)
• Mixed patterns — combinations of the above

Cytokeratin-7 (CK7) positivity is consistent with biliary tract origin ^[2]

Typical IHC profile of CCA:

This IHC panel is critical when distinguishing iCCA from HCC, especially when a liver mass is identified and biopsy is performed.

Classification by site: ^[4]

• Klatskin's tumour: cholangiocarcinoma that involves the common hepatic duct bifurcation (usually perihilar type) ^[4]

This classification describes the extent of ductal involvement and is crucial for surgical planning:

Bismuth-Corlette classification for perihilar tumour: ^[2][4]

Bile duct tumours that involve common hepatic duct bifurcation are referred to as Klatskin tumour regardless of whether they arise from intrahepatic or extrahepatic portion of biliary tree ^[2]

Note: iCCA, pCCA, and dCCA each have separate TNM staging systems because they behave as biologically distinct diseases.

Intrahepatic CCA (staged like liver tumours):

• T1a: Solitary ≤ 5 cm without vascular invasion
• T1b: Solitary > 5 cm without vascular invasion
• T2: Solitary with intrahepatic vascular invasion, OR multiple tumours
• T3: Tumour perforating visceral peritoneum
• T4: Direct invasion of local extrahepatic structures

Perihilar CCA:

• Staging considers depth of invasion into bile duct wall, hepatic artery, portal vein, and unilateral vs bilateral hepatic duct involvement

Distal CCA:

• Staged similarly to other pancreaticobiliary cancers, based on depth of invasion into bile duct wall and surrounding structures

Metastatic sites depend on type of cholangiocarcinoma: ^[2]

The clinical presentation of CCA depends heavily on anatomical location:

• Intrahepatic CCA behaves like a liver mass — often silent until large
• Perihilar CCA causes early biliary obstruction — presents with jaundice
• Distal CCA presents like other periampullary tumours — painless obstructive jaundice

Differential diagnosis: ^[2]

• Choledocholithiasis — intermittent jaundice, colicky pain, fluctuating LFTs
• Pancreatic cancer (head) — painless jaundice, Courvoisier's sign, weight loss
• Cancer of the ampulla of Vater — intermittent jaundice (tumour sloughs → obstruction relieved), better prognosis
• Viral hepatitis — hepatocellular pattern LFTs, viral markers positive
• Primary sclerosing cholangitis (PSC) — "beaded" appearance on MRCP, multifocal strictures
• Primary biliary cholangitis (PBC) — AMA positive, cholestatic LFTs, middle-aged women
• IgG4-related sclerosing cholangitis — important mimic! Responds to steroids; elevated IgG4 levels
• Mirizzi syndrome — extrinsic compression of CHD by impacted gallstone
• Benign biliary stricture — post-surgical, post-ERCP, chronic pancreatitis

• Hepatocellular carcinoma (HCC) — AFP elevated, arterial enhancement + washout on CT/MRI
• Liver metastases — look for primary tumour (CRC, breast, lung)
• Hepatic abscess — fever, leukocytosis, rim-enhancing lesion
• Haemangioma — peripheral nodular enhancement, centripetal fill-in
• Focal nodular hyperplasia — central scar, homogeneous enhancement

Key: Immunohistochemical stain is useful in differential diagnosis of cholangiocarcinoma with other malignancy ^[2] — CK7/CK19 positive for CCA vs. HepPar-1/Glypican-3/AFP positive for HCC

Key points from lecture slides ^[3]:

• Tumour markers: carcinoembryonic antigen (CEA), CA 19-9 (may or may not be elevated, nonspecific)
• USG, CT scan, MRI for diagnosis
• FNAC or Trucut biopsy (ONLY for unresectable cases) — because biopsy risks tumour seeding along the needle tract in potentially resectable disease
• Hepatic resection is the treatment of choice (resectability rate about 20%)
• Other treatment: no proven effect (this was 2019; now in 2025, gemcitabine-cisplatin ± durvalumab is standard for advanced CCA — TOPAZ-1 trial)

This is one of the most important clinical distinctions to make at the bedside. The history alone often tells you the answer ^[8]:

Why is stone jaundice intermittent but tumour jaundice progressive?

• A gallstone can act as a ball-valve — sometimes it obstructs the CBD, sometimes it dislodges and bile flows again. Hence the jaundice waxes and wanes.
• A tumour grows relentlessly. Once it narrows the duct, it only gets worse. The obstruction never relieves spontaneously.

Why is stone disease more commonly associated with fever?

• When a stone obstructs the CBD, stagnant bile becomes infected (bacteria from the duodenum reflux upwards). The stone creates a closed space → pressure builds → bacteria translocate into the bloodstream → cholangitis/sepsis.
• Tumours obstruct more gradually, and until the duct is completely occluded, some bile still flows → less stasis → less infection (until late stage).

Pathology causing malignant biliary obstruction: ^[9][10]

i. Cholangiocarcinoma at hilum (Klatskin tumour)

• Cholangiocarcinoma at hilum, Klatskin tumour ^[9]
• Obstruction to just left or right hepatic duct alone will not cause obstructive jaundice ^[1] — you need bilateral obstruction or obstruction at the confluence for clinical jaundice. Why? Because the contralateral liver lobe continues to excrete bilirubin through its unobstructed duct.

ii. Carcinoma of Head of Pancreas

• Carcinoma of pancreas ^[9]
• The most common cause of malignant obstructive jaundice overall
• 70% of pancreatic cancers are in the head → they compress or invade the intrapancreatic CBD → progressive painless jaundice
• Severe epigastric pain radiating to the back is characteristic (retroperitoneal infiltration of coeliac plexus) — but this is a feature of body/tail tumours rather than head tumours ^[11]
• Double duct sign on CT/MRCP: simultaneous dilatation of both the CBD and pancreatic duct — highly suggestive of pancreatic head cancer ^[11]

iii. Periampullary Carcinoma

• Periampullary carcinoma ^[9][10]
• This is a group term for tumours arising at or near the ampulla of Vater, including:
  • Carcinoma of the ampulla of Vater — has the best prognosis among periampullary tumours because it presents earlier (even a small tumour at the ampulla blocks bile flow and causes jaundice) ^[1]
  • Carcinoma of the duodenum ^[9][10]
  • Carcinoma of lower end of (distal) CBD ^[1]
  • Carcinoma of head of pancreas ^[1]
• These are grouped because their presentation (painless jaundice) and surgical management (Whipple procedure) are similar ^[1]

iv. Carcinoma of Gallbladder

• Carcinoma of gallbladder — cystic duct LN, direct infiltration of CBD, tumour fragments ^[9]
• Can cause obstructive jaundice by three mechanisms ^[1]:
  • Spread to cystic duct lymph nodes → extrinsic compression of CBD
  • Direct infiltration of CBD
  • Tumour fragments breaking off into the CBD

v. Hepatocellular Carcinoma (HCC)

• HCC — direct infiltration, compression, tumour fragments in CBD ^[9]
• Usually occurs when mass is situated near confluence site of left and right intrahepatic ducts ^[1]
  • From anterior liver = Segment 4/5 ^[1]
  • From posterior liver = Caudate segment (uncommon) ^[1]
• HCC causing obstructive jaundice is NOT common — it is much more likely to cause jaundice from loss of hepatic reserve in the cirrhotic liver ^[12]

vi. Secondary Lymphadenopathy

• Porta lymphadenopathy ^[10]
• Lymph node metastases to the coeliac axis or porta hepatis ^[13]
• Carcinoma of stomach with metastatic lymph node in the porta hepatis ^[13]
• GI malignancy (CRC), Lymphoma ^[1]
• Extrinsic compression of the bile duct by enlarged lymph nodes at the hepatoduodenal ligament

Benign causes of biliary obstruction: ^[1]

i. Choledocholithiasis

• Choledocholithiasis ^[2]
• Most common benign cause of obstructive jaundice
• Key differentiating feature: intermittent jaundice with pain and fever (Charcot's triad) vs. the painless progressive jaundice of CCA

ii. Primary Sclerosing Cholangitis (PSC)

• Primary sclerosing cholangitis (PSC) ^[2]
• Creates multifocal strictures with a "beaded" appearance on MRCP
• Important: PSC itself is a risk factor for CCA, and a dominant stricture in PSC may represent superimposed CCA → always suspect malignancy in any PSC patient with worsening jaundice or a new dominant stricture
• Common in Westerners, less common in Asia ^[3]

iii. IgG4-Related Sclerosing Cholangitis

• A critical mimic of CCA! Can produce a stricture that looks identical to CCA on imaging
• Elevated serum IgG4 level is a clue
• Responds dramatically to corticosteroids — which CCA obviously does not
• Always check serum IgG4 before assuming a biliary stricture is malignant ^[2]

iv. Primary Biliary Cholangitis (PBC)

• Primary biliary cirrhosis (PBC) ^[2] (now renamed Primary Biliary Cholangitis)
• Autoimmune destruction of small intrahepatic bile ducts
• Anti-mitochondrial antibody (AMA) positive
• Predominantly affects middle-aged women
• Causes intrahepatic cholestasis rather than extrahepatic obstruction — so it causes cholestatic LFTs and pruritus, but the bile ducts are NOT dilated on imaging

v. Other Benign Causes

• Blood clot (Haemobilia) / Mucus / Foreign body / Tumour thrombus ^[1]
• Benign strictures: TB, Autoimmune, Iatrogenic, RPC ^[1]
• Chronic pancreatitis, Pancreatic cysts ^[1]
• Mirizzi syndrome — common hepatic duct obstruction caused by extrinsic compression from an impacted stone in the cystic duct or Hartmann's pouch of the gallbladder ^[1]

How to distinguish iCCA from HCC on imaging?

• HCC: Arterial hyperenhancement → portal venous washout (the tumour "lights up then fades"). Classic LIRADS-5 pattern.
• iCCA: Peripheral arterial rim enhancement → progressive centripetal fill-in on delayed phase (because the dense desmoplastic stroma enhances slowly). Does NOT show washout.

Metastatic carcinoma to liver is commoner than primary liver cancer ^[15] Commonest site from GI tract (portal venous circulation): colorectal, stomach, pancreas ^[15]

• Always look for a primary source — CRC is the most common (CEA elevated), followed by gastric, pancreatic, breast, lung
• Elevated CEA or CA 19-9 in some cases with primary GI malignancy ^[15]
• Investigation for primary: CXR, endoscopy, CT scan abdomen ^[15]
• Multiple liver lesions with a known primary → likely metastatic rather than primary liver cancer

• Cysts (simple cyst, polycystic disease) ^[14]
• Liver abscess (pyogenic or amoebic) — fever, raised WCC, rim-enhancing lesion with internal debris
• Haematological malignancies (lymphoma, leukaemia, myeloproliferative disease) ^[14]

Before diving into individual tests, let's understand what we're trying to achieve when working up suspected cholangiocarcinoma. There are essentially five diagnostic goals, and every investigation serves at least one:

1. Confirm biliary obstruction — Is there truly an obstruction? At what level?
2. Characterise the lesion — Is it benign or malignant? What type of malignancy?
3. Define the anatomy — Exactly where is the tumour? How far does it extend along the ducts?
4. Stage the disease — Is there vascular invasion? Nodal metastasis? Distant metastasis?
5. Assess resectability — Can we offer curative surgery? Is the future liver remnant (FLR) adequate?

There is no single diagnostic criterion for CCA (unlike, say, the Tokyo Guidelines for cholangitis). The diagnosis is established through a combination of clinical features, biochemistry, imaging, and histology. Let me walk you through each component systematically.

• Jaundice ^[2] — scleral icterus first (detectable at bilirubin > 35–40 µmol/L)
• Cachexia, pallor ^[14] — suggests advanced malignancy
• Lymphadenopathy ^[14] — check left supraclavicular (Virchow's node), periumbilical (Sister Mary Joseph nodule)
• Chronic stigmata of liver disease ^[14] — spider naevi, palmar erythema, gynaecomastia → suggests underlying cirrhosis

• Hepatomegaly – size, tenderness, consistency, surface, edge, bruit ^[14]
  • iCCA: palpable mass with firm/hard consistency, irregular surface
  • Extrahepatic CCA: hepatomegaly from biliary obstruction (smooth, non-tender)
• Right upper quadrant tenderness ^[2]
• Palpable gallbladder ^[2]
  • Courvoisier's law: In painless jaundice if the gallbladder is palpable, it is unlikely to be due to gallstones and points towards biliary or pancreatic malignancy (lower end of CBD / head of pancreas / ampulla of Vater) ^[2]
  • Why does Courvoisier's law work? Gallstones develop chronically → chronic cholecystitis → fibrosed, contracted gallbladder → cannot distend. Malignant obstruction is "acute" to the gallbladder (the gallbladder was previously healthy) → distends with mucus under back-pressure ^[16]
  • Remember: Courvoisier's sign is positive only in distal CCA (obstruction below cystic duct insertion). In perihilar CCA (Klatskin tumour), the obstruction is ABOVE the cystic duct → gallbladder cannot fill → Courvoisier's sign is NEGATIVE
• Other organomegaly (spleen), mass, ascites ^[14]
• PR examination ^[14] — check for Blumer's shelf (peritoneal drop metastasis)

• Anaemia — anaemia of chronic disease (normocytic normochromic) in malignancy; or iron deficiency from chronic blood loss
• Leukocytosis — if superimposed cholangitis; or pancytopenia if underlying cirrhosis with hypersplenism ^[16]
• Thrombocytopenia — important to check before any invasive procedure (ERCP, PTC, biopsy) ^[16]

• ↑ PT/INR ^[2]
• Why? Biliary obstruction → no bile salts in gut → no fat absorption → no absorption of fat-soluble vitamins (A, D, E, K) → Vitamin K deficiency → impaired synthesis of clotting factors II, VII, IX, X → prolonged PT/INR ^[16]
• Clinical importance: Must correct coagulopathy before any invasive procedure (give IV Vitamin K or FFP). This is also important pre-operatively.

This is where understanding the pattern matters more than individual values:

Key pattern recognition:

• Cholestatic pattern (ALP >> ALT): Suggests biliary obstruction → think CCA, CA pancreas, CBD stones
• Hepatocellular pattern (ALT >> ALP): Suggests hepatitis, drug injury → less likely CCA
• In CCA, expect cholestatic pattern with conjugated hyperbilirubinaemia ^[4]

• Hypercalcemia and hypophosphatemia ^[2]
  • Hypercalcemia of malignancy associated with low PTH and vitamin D levels ^[2]
  • Mechanism: PTHrP secretion by tumour (humoral hypercalcaemia of malignancy) — this is uncommon in CCA but can occur

• HBV and HCV serology ^[14]
• Why? To assess for underlying chronic liver disease/cirrhosis which affects both aetiology and surgical planning (cirrhotic livers tolerate less resection)

• Serum AFP: Differentiate between intrahepatic cholangiocarcinoma and HCC ^[2]
• AFP is typically normal in pure CCA
• Rare combined hepatocellular-cholangiocarcinoma tumour may have high levels of AFP ^[2]
• AFP sensitivity in cholangiocarcinoma is only ~10% ^[17]
• In contrast, AFP is elevated in 70–90% of HCC

• Serum IgG4: Evaluate for the possibility of IgG4-related sclerosing cholangitis ^[2]
• Why is this critical? IgG4-related sclerosing cholangitis is the most important benign mimic of CCA. It creates strictures that look identical on imaging. If you miss it, you may subject a patient to unnecessary major hepatectomy for a disease that responds to steroids.

USG, CT scan, MRI ^[3]

USG is always the initial imaging test ^[2]. It is cheap, non-invasive, widely available, and radiation-free. Here's what it tells you:

What to look for:

Why does the level of ductal dilatation tell you the level of obstruction?

• If only intrahepatic ducts are dilated but the CBD is normal → the block is at the hilum (perihilar CCA)
• If both intrahepatic and extrahepatic ducts are dilated → the block is at the distal CBD (distal CCA or pancreatic head cancer)
• This is analogous to diagnosing the level of a river dam by seeing which tributaries are flooded

Invasion into portal vein or hepatic artery is an important finding as it may indicate surgical unresectability ^[2]

Normal bile duct measurements:

• Intrahepatic ducts: normally < 2–3 mm (often not visible on USG) ^[16]
• CBD: normal ≤ 6–8 mm in adults; CBD > 0.8 cm is pathological ^[16]
• CBD limit: 0.1 cm for every 10 years old (i.e., acceptable CBD diameter increases slightly with age and post-cholecystectomy) ^[8]

Contrast-enhanced multidetector-row helical triphasic CT scan ^[2]:

• Indicated in patients with suspected perihilar or intrahepatic cholangiocarcinoma ^[2]

What CT tells you (the 4 key questions):

Why triphasic (three phases)?

• Arterial phase: Shows hepatic arterial anatomy (surgical planning) and tumour arterial enhancement
• Portal venous phase: Shows portal vein anatomy, portal vein invasion/thrombosis, and liver parenchymal enhancement
• Delayed phase (equilibrium): Critical for CCA — the desmoplastic stroma of CCA enhances LATE, so delayed-phase images show the tumour best. This distinguishes CCA from HCC (which washes out on delayed phase)

CT-guided biopsy can be obtained if a mass lesion is seen, with a risk of seeding the biopsy tract with malignant cells ^[2]

Lower sensitivity than MRI scan to detect extra-regional nodal disease such as metastasis to periaortic, pericaval or celiac artery LN and peritoneum ^[2]

• Endoscopic ultrasound ± FNAC or brush cytology ^[2]
• Indicated in patients with suspected distal extrahepatic cholangiocarcinoma ^[2]
• Enable biopsy with FNA or brush cytology ^[2]
• Assess local extent of primary tumour and status of regional LNs ^[2]
• Staging: EUS for nodal involvement ^[4]
• EUS is particularly good for:
  • Distal CBD lesions (the EUS transducer in the duodenum is very close to the distal CBD)
  • Regional lymph node sampling (EUS-guided FNA of suspicious nodes)
• Limitation: Not useful for perihilar lesions (too far from the EUS transducer) ^[16]

• PET scan with fluorodeoxyglucose (FDG) contrast ^[2]
• Evaluate for occult distant metastasis that MRCP and MDCT are unable to detect ^[2]
• FDG-PET detects metabolically active tissue — CCA cells have high glucose uptake (Warburg effect)
• Sensitivity: Good for mass-forming iCCA (~85–95%); lower for perihilar CCA (~50–60%) because the sclerosing/infiltrating growth pattern has less tumour cellularity and more fibrosis
• Main role: Detecting occult metastases (e.g., distant lymph nodes, peritoneal disease, bone) that would change management from curative to palliative
• Limitation: False positives in cholangitis, granulomatous disease, or any inflammation

• Staging: staging laparoscopy ^[4]
• Performed before committing to major hepatectomy
• Detects peritoneal metastases and small liver surface metastases that CT/MRI cannot see
• Yield: Upstages ~25–30% of patients thought to be resectable on cross-sectional imaging → avoids unnecessary laparotomy
• Particularly useful for perihilar CCA (Bismuth III/IV) and iCCA with high CA 19-9

FNAC or Trucut biopsy (ONLY for unresectable cases) ^[3] Tissue diagnosis (not must): brush cytology/CT-guided biopsy if uncertain ^[4] Biopsy: fine needle aspiration cytology (FNAC), Trucut biopsy ^[14]

Why NOT biopsy potentially resectable CCA?

• Needle-tract seeding: CCA cells can implant along the biopsy tract → peritoneal or abdominal wall metastasis → converting a potentially curative situation into an incurable one
• If imaging and clinical features strongly suggest CCA AND the tumour is resectable → proceed directly to surgery without pre-operative tissue confirmation
• Tissue diagnosis is only required when:
  1. The patient is unresectable and needs histological confirmation before starting chemotherapy
  2. There is diagnostic uncertainty (e.g., cannot distinguish from IgG4-cholangitis, lymphoma, or metastatic disease)
  3. CT failed to demonstrate typical features, before chemotherapy, or suspected secondary metastasis ^[11]

Immunohistochemical stain is useful in differential diagnosis of cholangiocarcinoma with other malignancy ^[2]

Before we go into specific treatments, let's understand the strategic logic of managing CCA. There are only three questions you need to answer, in this exact order:

1. Is the patient septic? → If yes, treat the sepsis FIRST (biliary drainage + antibiotics)
2. Is the tumour resectable? → If yes, surgery is the ONLY curative option
3. Is the patient fit for surgery? → If no, palliate

Everything else flows from these three decisions.

Management: ^[18]

• Treat SEPSIS
• Assess tumour resectability + Patient general fitness + Liver function reserve
• Resectable → Surgery; Non-resectable → Palliation

Criteria of resectability: ^[18]

• No distant metastases
• SMA and celiac axis not involved
• Patent superior mesenteric-portal venous confluence
• PV involvement is NOT absolute contraindication ^[18]
  • Venous resection is appropriate to improve resectability and achieve R0 resection ^[18]
  • Significant morbidity and mortality ^[18]
  • Reasonable survival: median = 13 months, 5-year = 7% ^[18]

Unresectable if: ^[4]

• Invasion of major vessels (e.g. main PV, main hepatic artery, celiac trunk, SMA, SMV) ^[4]
• Extensive involvement of biliary tree (bilaterally > 2° radicles) ^[4] — meaning the tumour extends beyond the second-order bile duct branches on BOTH sides. Why does this make it unresectable? Because even if you resect the extrahepatic bile ducts, you cannot reconstruct drainage from both sides if the 2nd-order branches are involved bilaterally — there would be insufficient healthy duct to anastomose to a jejunal loop.
• LN metastasis (retropancreatic, paracoeliac, paraaortic) ^[4] — these are considered distant (M1) nodes, indicating systemic disease
• Distal organ metastasis (lung, peritoneum) ^[4]

Additional criteria ^[2]:

• Bilateral or multifocal intrahepatic disease ^[2]
• Hepatic artery and portal vein invasion (bilateral main branches) ^[2]
• Extrahepatic adjacent organ invasion ^[2]

Assessment of patient status: ^[16]

• Age / Concomitant medical illness
• Hidden medical illness = CXR / ECG / Spirometry
• Nutrition = LFT
• Fluid and electrolytes = RFT
• Coagulopathy = CBC / Clotting profile

Assessment of tumour status: ^[16]

• Clinical signs of inoperability:
  • Irregular surface hepatomegaly
  • Troisier's sign (Virchow's node) — left supraclavicular LN
  • Blumer's shelf — peritoneal metastasis
  • Sister Mary Joseph nodules — peritoneal metastasis
  • Ascites — peritoneal metastasis

For perihilar CCA, major hepatectomy is often required. You need to ensure the patient will have enough functioning liver left after resection:

• FLR must be > 25–30% of total liver volume in a normal liver
• FLR must be > 40% in a cirrhotic or cholestatic liver (impaired regeneration capacity)
• If FLR inadequate: portal vein embolisation (PVE) to induce atrophy of affected segment + hypertrophy of unaffected segments ^[4]
  • Why does PVE work? By embolising the portal vein branch feeding the side to be resected, you redirect portal blood flow to the contralateral lobe → that lobe hypertrophies over 4–6 weeks → now the FLR is large enough to sustain life after resection. Essentially you are "training" the liver before surgery.

Reasons why MBO is high risk for operation and measures to reduce complications: ^[16]

• Cancer cachexia → Malnutrition → Nutritional support
• Liver derangement → Bleeding tendency → IV Vitamin K and FFP during surgery
• Superimposed biliary infection → Antibiotics cover

Why drain pre-operatively? A jaundiced liver is a sick liver. Biliary obstruction causes:

• Impaired hepatocyte function (cannot synthesise clotting factors, albumin)
• Vitamin K malabsorption → coagulopathy
• Impaired reticuloendothelial function → susceptibility to sepsis
• Impaired wound healing (poor protein synthesis) Operating on a deeply jaundiced patient → high risk of post-operative liver failure, bleeding, and sepsis.

Theoretically: Do NOT need to drain if no sepsis + early surgery can be offered within 1–2 weeks ^[16]

• Pre-operative drainage itself carries risks (cholangitis, pancreatitis, stent complications)
• Some evidence suggests it increases overall complications even in expert centres

Practically (QMH): Drain ALL patients since QMH cannot offer early surgery ^[16]

• Whipple operation has to wait for 6–8 weeks and the chance of biliary sepsis will be very high without drainage while waiting for this period ^[16]

No promise of resection until laparotomy finding documents absence of spread ^[16] Look for peritoneal nodules after laparotomy before resection and send for frozen section to rule out malignancy if suspicious ^[16]

• Upstages ~25–30% of patients thought to be resectable on cross-sectional imaging
• Particularly important for Bismuth III/IV perihilar CCA, and any case with high CA 19-9

Intrahepatic: partial hepatectomy + portal LN dissection ^[4]

Perihilar: extrahepatic bile duct resection + cholecystectomy + portal LN dissection (± partial hepatectomy) + reconstruction (Roux-en-Y hepaticojejunostomy) ^[4]

This is the most surgically complex subtype. The operation must remove the tumour-bearing bile duct AND any liver lobe with involved duct branches, while preserving enough liver to sustain life.

Detailed surgical approach by Bismuth type: ^[2]

Why is the Roux-en-Y hepaticojejunostomy (HJ) necessary? Once you resect the extrahepatic bile ducts, you have cut the bile "highway" between liver and gut. You need to reconnect the remaining hepatic duct stump(s) to a loop of jejunum so bile can drain into the intestine. A Roux-en-Y configuration is used (defunctionalised jejunal limb) to prevent reflux of intestinal contents into the biliary tree, which would cause ascending cholangitis.

Distal CBD tumour: Whipple's procedure (pancreaticoduodenectomy) ^[4]

The Whipple procedure removes:

• Head of pancreas
• Duodenum (D1–D3)
• Distal CBD
• Gallbladder
• ± Distal stomach (classic Whipple) or pylorus-preserving (PPPD)

Why such an extensive operation for a bile duct tumour? Because the distal CBD runs through the head of the pancreas and behind the duodenum. You cannot resect just the distal CBD without removing the surrounding structures that share the same blood supply (the pancreaticoduodenal arteries supply all these structures en bloc). Removing one without the others would leave devascularised tissue.

Reconstruction after Whipple (3 anastomoses):

1. Pancreaticojejunostomy — reconnect pancreatic remnant to jejunum
2. Hepaticojejunostomy — reconnect bile duct to jejunum
3. Gastrojejunostomy (or duodenojejunostomy in PPPD) — reconnect stomach/duodenum to jejunum

Current standard (2025):

• Capecitabine for 6 months — this became standard after the BILCAP trial (2019), which showed significantly improved overall survival in resected biliary tract cancers (including CCA) with adjuvant capecitabine vs observation
• Alternatives: ^[2]
  • Gemcitabine
  • Capecitabine
  • Leucovorin-modulated fluorouracil (5-FU)

Why capecitabine? Capecitabine ("cape" = capacity to become 5-FU) is an oral prodrug that is converted to 5-FU preferentially in tumour tissue by thymidine phosphorylase (which is overexpressed in tumour cells). This provides targeted drug delivery with less systemic toxicity than IV 5-FU.

• Role: Very select patients with perihilar CCA (unresectable by conventional surgery but no distant metastases) may be considered for liver transplantation
• This follows the Mayo Clinic protocol: neoadjuvant chemoradiation → staging laparoscopy → liver transplant
• Strict selection criteria: tumour ≤ 3 cm, no intrahepatic/extrahepatic metastasis, arising in PSC background
• 5-year recurrence-free survival ~65–70% in selected patients
• Not widely available and requires a specialised transplant centre with dedicated protocol

Current standard (2025): Gemcitabine + Cisplatin + Durvalumab

• TOPAZ-1 trial (Oh et al., NEJM Evidence 2022): Adding durvalumab (anti-PD-L1 immune checkpoint inhibitor) to gemcitabine-cisplatin improved overall survival in advanced biliary tract cancer (median OS 12.8 vs 11.5 months; 2-year OS 24.9% vs 10.4%)
• This is now the global standard first-line regimen

Previous standard: Gemcitabine + Cisplatin (GemCis)

• Established by the ABC-02 trial (Valle et al., NEJM 2010)
• Remains the backbone; durvalumab is added on top

Molecular-targeted therapies (precision oncology):

Why is molecular profiling now essential? Because ~40–50% of iCCA and ~15–25% of extrahepatic CCA harbour actionable mutations. All patients with advanced CCA should undergo comprehensive genomic profiling (next-generation sequencing) to identify targetable alterations.

Surgical bypass ^[2] — reserved for patients found to be unresectable at laparotomy, or those with expected survival > 6 months where stent complications would be problematic.

Single bypass = Hepaticojejunostomy / Choledochojejunostomy ^[16]

• Just bypasses the biliary tree
• Hepaticojejunostomy refers to anastomosis between common hepatic duct and jejunum ^[16]

Double bypass = + Gastrojejunostomy ^[16]

• Bypasses both biliary tree AND enteric obstruction
• Especially for CA head of pancreas since apart from compression on bile duct it also compresses on duodenum to cause gastric outlet obstruction (GOO) ^[16]

Triple bypass = + Pancreaticojejunostomy ^[16]

• Bypasses biliary tree, enteric obstruction AND pancreatic duct
• Pancreatic duct is small and anastomosis is difficult to achieve which leads to high risk of anastomotic leakage ^[16]

Stenting vs Surgical Bypass — Comparison

Comparison between stenting/PTBD with surgical bypass as palliative treatment: ^[16]

Bottom line: Stenting is preferred for patients with short expected survival ( < 6 months) or poor fitness. Surgical bypass is better for patients with longer expected survival who can tolerate surgery.

Photodynamic therapy: ^[2]

• Involves injection of IV porphyrin photosensitizer followed by the endoscopic application of light of a specific wavelength to the tumour bed ^[2]
• The photosensitizer accumulates preferentially in tumour cells → when activated by specific wavelength light → generates reactive oxygen species → local tumour necrosis
• Improves biliary drainage and may improve survival in perihilar CCA when combined with stenting
• Not widely available; considered in specialised centres for non-resectable perihilar CCA

Pain control ^[19]

• Analgesics: WHO pain ladder (paracetamol → weak opioids → strong opioids such as morphine)
• Celiac plexus block ^[16]
  • Endoscopic USG / CT-guided celiac plexus neurolysis ^[21]
  • Why does this work? The celiac plexus (located at the aortic bifurcation at T12–L1) transmits visceral pain from the upper abdominal organs including the biliary tree and pancreas. Chemical neurolysis (injection of absolute alcohol or phenol) destroys these pain fibres → dramatic pain relief
  • Particularly effective for pancreatic/biliary cancer pain that is refractory to opioids

• Nutritional support: Oral nutritional supplements, pancreatic enzyme replacement (if Whipple was considered but not done — these patients often have pancreatic exocrine insufficiency from bile duct obstruction affecting the pancreatic duct)
• Pruritus management: Cholestyramine (bile acid sequestrant), rifampicin, naltrexone, sertraline
• Duodenal stenting or gastrojejunostomy if gastric outlet obstruction develops

Cause of mortality in MBO: Biliary sepsis ^[22][23]

Pathophysiology: CCA obstructs the bile duct → bile stasis → bacterial colonisation of stagnant bile (normally, bile is kept sterile by constant antegrade flow and the sphincter of Oddi acting as a valve against duodenal reflux). Once bile is stagnant:

Biliary obstruction + infection → Normal ductal pressure: 7–14 cm H₂O → Increased biliary pressure > 25 cm H₂O → Bacteria reflux to hepatic veins and lymphatics → Bacteraemia and septic shock ^[24]

Excretion of antibiotics is impaired in biliary obstruction ^[24] — this is why antibiotics alone are often insufficient; biliary drainage is mandatory.

Common organisms: Gram-negative rods (E. coli, Klebsiella) > Enterococcus > Pseudomonas (especially if stent in situ) ^[19]

Clinical presentation:

• Charcot's triad (fever + jaundice + RUQ pain) → 50–70% of cholangitis cases
• Reynolds pentad (+ shock + confusion) → < 10%, indicates suppurative cholangitis with septic shock

Why is cholangitis so dangerous in CCA patients? Because these patients have:

• Already impaired hepatic immune function from biliary obstruction (see below)
• Often pre-existing malnutrition from cancer cachexia
• A permanent nidus of infection (the obstructed, stagnant bile cannot be sterilised without drainage)
• If a palliative stent is in place → the biliary stent in-situ serves as a foreign body nidus for infection ^[19]

Cause of mortality in MBO: Liver failure ^[22][23]

Pathophysiology — the cascade of hepatic decompensation:

Pathophysiological effects of malignant biliary obstruction: ^[25]

• Impaired protein synthesis → hypoalbuminaemia → oedema, ascites, poor wound healing
• Impaired clotting factor synthesis → coagulopathy → bleeding tendency
• Impaired gluconeogenesis → hypoglycaemia (especially in the fasted state)
• Impaired ketogenesis → cannot switch to fat as fuel during starvation → accelerated malnutrition
• Endotoxaemia → gut-derived endotoxins normally cleared by Kupffer cells in the liver; when biliary obstruction impairs Kupffer cell function → endotoxins enter the systemic circulation → SIRS, organ dysfunction
• ↓ Reticuloendothelial function → impaired clearance of bacteria and toxins → increased susceptibility to infection
• ↓ Cell-mediated immunity → impaired T-cell function → further susceptibility to sepsis

Why does biliary obstruction impair liver function? Bile duct obstruction → back-pressure of bile → cholestasis → bile acids accumulate in hepatocytes → bile acid toxicity damages hepatocyte mitochondria and cell membranes → hepatocyte necrosis and apoptosis → progressive loss of functional liver mass. Simultaneously, periductal inflammation and fibrosis from the tumour itself further destroys liver parenchyma.

Why is malignant biliary obstruction so risky for operation? ^[23]

• Cancer cachexia → malnutrition
• Liver function impairment
• Superimposed biliary infection

These three factors combine to create a "perfect storm" of operative risk: a malnourished patient with a failing liver, impaired immunity, and active or potential infection. This is why pre-operative optimisation (biliary drainage, nutritional support, treating sepsis) is so critical.

Cause of mortality in MBO: Cancer cachexia ^[22][23]

Pathophysiology: CCA causes cachexia through two synergistic mechanisms:

1. Tumour-mediated cachexia: Pro-inflammatory cytokines (TNF-α/"cachectin", IL-6, IL-1β) secreted by the tumour and host immune cells → increased basal metabolic rate + skeletal muscle proteolysis + lipolysis + anorexia via hypothalamic appetite suppression
2. Bile salt malabsorption: No bile salts in the duodenum → impaired fat emulsification → fat malabsorption → steatorrhoea → loss of calories and fat-soluble vitamins (A, D, E, K)
   • Vitamin K deficiency → impaired synthesis of clotting factors II, VII, IX, X → bleeding tendency (prolonged PT/INR) ^[16]
   • Vitamin D deficiency → osteomalacia, hypocalcaemia
   • Vitamin A deficiency → night blindness (rare, requires prolonged obstruction)

Progressive biliary obstruction is the hallmark of extrahepatic CCA. Beyond just turning the patient yellow, obstructive jaundice has wide-ranging systemic effects:

CCA spreads via several routes, each causing specific complications:

CCA can cause portal hypertension through:

• Direct portal vein invasion — the most common mechanism in perihilar CCA; tumour encases or occludes the main portal vein or its branches
• Secondary biliary cirrhosis — prolonged biliary obstruction → chronic cholestasis → periportal fibrosis → cirrhosis → portal hypertension ^[22]
• Consequences of portal hypertension: ascites, splenomegaly, oesophageal/gastric varices → upper GI bleeding

• Locally advanced distal CCA or pancreatic head invasion can compress the duodenum
• Presents with vomiting, early satiety, inability to tolerate oral intake
• Management: endoscopic duodenal stenting or gastrojejunostomy (double bypass) ^[16]

Haemobilia (UGIB from biliary tree) ^[4]

Pathophysiology: Tumour erodes into a branch of the hepatic artery or portal vein within the bile duct wall → blood enters the biliary tree → passes through the ampulla into the duodenum → presents as melaena or haematemesis. Classic triad of haemobilia = jaundice + biliary colic + GI bleeding (Quincke's triad).

Can also occur iatrogenically from:

• PTC/PTBD (needle punctures hepatic artery or portal vein in the portal triad) ^[16]
• Post-surgical bleeding from hepatic resection surface draining into the biliary tree

Complications: ^[4][16]

• Stent occlusion (sludge / tumour ingrowth / tumour overgrowth) ^[16]
  • Why does this happen? Uncovered metallic stents have open mesh → tumour grows through the mesh interstices (ingrowth) or extends beyond the stent ends (overgrowth). Biliary sludge (a mixture of bacteria, calcium bilirubinate, and proteinaceous debris) also deposits on stent surfaces.
  • Management: sweeping or placing new stent ^[4]
  • Stent occlusion typically presents with recurrent jaundice ± cholangitis weeks to months after stent placement
• Stent migration ^[4][16]
  • More common with plastic stents; can migrate proximally (into the liver) or distally (into the duodenum)
• Cholangitis / Cholecystitis ^[16]
  • Stent insertion disrupts the normal barrier at the ampulla → bacterial contamination of the biliary tree → ascending cholangitis
  • Stents that occlude the cystic duct opening can cause acute cholecystitis
• Pancreatitis — ERCP manipulation at the ampulla can cause papillary oedema → pancreatic duct obstruction → post-ERCP pancreatitis (occurs in ~3–10% of ERCP procedures)
• Perforation — rare but life-threatening; duodenal perforation from endoscope or sphincterotomy
• Bleeding — from sphincterotomy site, or hepatic artery/portal vein injury during PTBD

Pre-op biliary drainage has increased risk of serious complications: ^[26] Pancreatitis (7%), cholangitis (26%), blocked stent (15%), bleeding (2%), perforation (2%) ^[26]

Specific PTBD complications:

• Bleeding is common due to puncture of hepatic artery or portal vein before reaching the bile duct (Portal triad) ^[16]
• Hemobilia (communication of the tract with a major vascular structure) ^[16]
• Fluid and electrolyte loss from external bile drainage (bile contains ~600–1000 mL/day of fluid rich in sodium, bicarbonate, and chloride)
• Catheter dislodgement → bile peritonitis

General Surgical Complications (Post-hepatectomy / Post-Whipple)

Early complications:

Complications specific to Whipple procedure (distal CCA): ^[16]

Late complications of Whipple procedure:

Late complications specific to hepaticojejunostomy:

• Most frequent long-term complication of Roux-en-Y hepatojejunostomy is stenosis of biliary-enteric anastomosis leading to jaundice, cirrhosis or cholangitis ^[22]
  • Why does anastomotic stricture occur? Chronic inflammation, ischaemia of the anastomotic site, and scar contracture → progressive narrowing → recurrent cholestasis and cholangitis
  • Management: percutaneous balloon dilatation (PTC access), or surgical revision

Common adverse effects of the regimens used in CCA: