Intrahepatic and Lower duct Cholangiocarcinoma

Intrahepatic cholangiocarcinoma needs to be differentiated from other tumors of liver including varieties of secondary tumors, similarly cholangiocarcinoma of lower bile duct origin should carefully be differentiated from tumors of pancreas, chronic pancreatitis and tumors of duodenum. A brief review of the problem has been posted:

Intrahepatic and Lower duct Cholangiocarcinoma
Lower duct cholangiocarcinomas
Rationale for diagnosis and surgical staging

• These tumours are located in the part of the bile duct that lies in the head of the pancreas or at the level of the first part of the duodenum.
  
• They are one of the members of the tetrad of 'periampullary tumours',which commonly present with obstructive jaundice.
  
• The group also includes cancers of the ampulla of Vater, duodenum and pancreas, the last being by far the commonest of the four.
  
• Presumably all three subtypes of cholangiocarcinoma can occur in this region but, as the MF (mass-forming) type would be very difficult to differentiate from pancreas cancer and as the IG (Intraductal-growing) type is very uncommon, it is the cicatrizing PI (Periductal-infiltrating) type that is usually recognized.
  

Diagnosis
In the patient presenting with jaundice, axial imaging may or may not demonstrate a pancreatic mass.

• If mass is present, the diagnosis is taken to be other than cholangiocarcinoma, either a malignancy of the head of the pancreas or focal pancreatitis, although, as already stated, some of these may actually be MF cholangiocarcinoma.
  
• When no mass is present, then cholangiocarcinoma is a possibility.
  

Surgical staging
When the tumours are at the upper border of their range at the level of the duodenum, involvement of the portal vein and hepatic artery is possible.

• The extent of the tumour in the bile duct is rarely a staging question as the treatment is a Whipple procedure in which the entire common bile duct is removed along with the gallbladder and cystic duct.
  

Diagnostic and staging tests
If the initial diagnostic test for painless jaundice is a CT scan, as we recommend, then the findings will be those of obstruction of the bile duct in the intrapancreatic portion with no mass.

• Dilation of the bile ducts may terminate anywhere from the upper border of the pancreas to the duodenum depending on the extent of the tumour.
  
• MRI or ERCP are currently both good choices as the second test under these conditions, and there are no evidence-based data to select between them.
  
• The former test is less invasive but also less informative.
  
• ERCP provides an endoscopic view of the duodenum that allows identification and biopsy of ampullary and duodenal tumours, which may block the bile duct and produce jaundice without being seen as a mass on CT scan, and MRI is less informative in this regard.
  
• ERCP may provide a tissue diagnosis and decompress the bile duct when that is desirable. On the other hand, ERCP requires the placement of a stent into the obstructed duct, and complications such as pancreatitis and haemorrhage have occurred.
  
• Both tests will confirm the presence of a bile duct stricture and display its form, although direct cholangiography is still somewhat superior.
  

The MRI characteristics are those for a PI as described under hilar cholangiocarcinoma.
Focal strictures, especially those with shoulders, suggest malignancy.

• Long tapering strictures limited to the intrapancreatic portion of the bile duct suggest chronic pancreatitis.
  
• Concomitant narrowing of the pancreatic duct in the head of the pancreas (double duct sign) suggests the presence of a small pancreatic cancer, not visible on CT scan.
  
• Longer or multiple pancreatic strictures suggest chronic pancreatitis.
  
• A single focal bile duct stricture in the absence of pancreatic duct abnormalities is the hallmark of cancer of the lower bile duct.
  
• Infiltrating cancers of the bile duct may cause more than one stricture along the bile duct but, when more than one stricture is present, other diagnoses such as PSC should be considered.
  
• Patients with the classical double duct sign or single focal shouldered bile duct strictures are likely to have small pancreatic or bile duct tumours.
  

Further diagnostic support is usually not needed prior to laparotomy, although it is reassuring when the CA19-9 is over 100 U. When doubt persists after ERCP or MRI, EUS is often quite useful.

• EUS may identify a small mass not seen on CT scan and biopsies may be obtained.
  
• Occasionally, enlarged lymph nodes are seen by EUS, and these may also be biopsied. However, negative EUS biopsies in patients who present with painless jaundice do not exclude malignancy and, for such a patient with an identifiable mass on EUS, pancreatoduodenectomy is recommended, even in the presence of negative EUS-guided biopsy.
  

If a non-operative approach is followed, short-term follow-up at 4–6 weeks with repeat imaging and biopsy is mandatory.

• If findings persist, then laparotomy is advisable.
  
• At laparotomy, detection of a mass by palpation or intraoperative ultrasound is reasonable evidence of malignancy, and a pancreatoduodenectomy should be performed.
  
• In the absence of a mass and where clinical or imaging results suggest a benign aetiology for the stricture, ultrasound-guided core biopsies of the bile duct stricture may be helpful in avoiding pancreatoduodenectomy.
  

Intrahepatic cholangiocarcinoma
Diagnosis
Clinical diagnosis of the common MF type is dependent on the presence of a liver mass that resembles a metastasis on axial imaging, such as MRI or CT scan, in a patient without a history of liver disease or evidence of an extrahepatic primary.

• The presence of an elevated serum CA19-9 level is helpful.
  
• To rule out primary tumours in the intestine, upper and lower endoscopy is usually performed.
  
• FDG-PET scan and mammography are other imaging tests that have been used to search for an extrahepatic primary.
  
• The pathological diagnosis may be made by needle biopsy, but this is required only when diagnostic doubt exists.
  

Surgical staging
The aim again is subservient to the surgical goals of removal of gross and microscopic tumour, while preserving adequate liver function. The questions to be answered are similar to those for cholangiocarcinoma, although the vessels in question are the intrahepatic arteries and veins including the hepatic veins.

• Atrophy is less of an issue as it is almost always on the side to be resected, as is the case for the extent of bile duct involvement in the PI and IG types.
  

Diagnostic and staging tests
MRI

• The MF type usually appears as an unencapsulated tumour, hypointense on T1-weighted images and hyperintense on T2- weighted images, although the pattern varies depending on the presence of fibrosis, necrosis and mucin in the tumour.
  
• Hypointensity on T2-weighted images may be seen especially in larger tumours.
  
• In these cases, differentiation from the central scar of focal nodular hyperplesia (FNH) is usually possible by the use of gadobenate dimeglumine (Gd BOPTA).
  
• With dynamic imaging, peripheral enhancement with progressive filling towards the centre of the lesion is common.
  
• Satellite lesions are frequent as is capsular retraction.
  
• The PI type appears as a thickened branching spiculated duct with dilation of the ducts peripheral to the tumour, i.e., much like the PI type of hilar tumour but displaced beyond the sectional ducts.
  
• In later stages, the surrounding liver may appear to be invaded.
  
• The IG type is seen as an intraductal enhancing mass with dilation of ducts peripheral to the mass.
  
• The intrahepatic variant otherwise has the characteristics of the hilar type and, indeed, this tumour may exist at any and all levels of the biliary tree.
  

Computerized tomography
The typical appearance of the MF lesion is of a large hypoattenuating irregular mass, minimally enhancing at the periphery, sometimes with calcifications and often with capsular retraction,satellite lesions and enlarged malignant-appearing periportal nodes.

Sonography
MF tumours are usually hypoechoic, but may be isoechoic or hypoechoic and homogeneous or heterogeneous. There are no features that differentiate them from metastatic disease, although peripheral ductal dilation is more common in cholangiocarcinoma.

ERCP
ERCP may be helpful in the PI and IG types when the diagnosis is unclear or after MRI when the extent of the tumour in the ducts is incompletely elucidated.

Differential diagnosis
Hilar and lower duct cholangiocarcinomas

1. Primary sclerosing cholangitis
   
2. Eosinophilic cholangitis and lymphoplasmocytic cholangitis
   
3. Benign inflammatory tumours
   
4. Cholelithiasis and choledocholithiasis
   
5. Adenoma of the bile duct
   
6. Carcinoma of the gallbladder
   
7. Neuroendocrine cancer of the bile duct
   
8. Granular cell tumours
   
9. Sarcoma of the bile duct
   
10. Lymph nodes
    

Intrahepatic cholangiocarcinoma

1. Hepatocellular carcinoma
   
2. Secondary tumours
   
3. Angiosarcoma
   
4. Epithelioid haemangioendothelioma (EHE)
   
5. Primary hepatic lymphoma
   
   

Dr. Jitendra Agrawal, Kanpur, India.