The most common presenting symptom of cholangiocarcinoma, leading to diagnostic work-up, is jaundice. The first-line imaging modality to explore the biliary system is ultrasonography, which depicts well the dilation of intra- and extra-hepatic bile ducts. However, ultrasound is poorly accurate in depicting the morphology of the bile duct stricture, and may not visualize the primary neoplasm. In fact, extra-hepatic cholangiocarcinoma may not form a mass, but may rather grow within the common bile duct walls. 

In jaundiced patients, it may be necessary to place a stent (a small tube made of plastic or of metal) to relieving the blocked common bile duct and resolve jaundice. This is usually done through an endoscopic procedure called ERCP (endoscopic retrograde cholangiopancreatography). The procedure consists of two distinct phases:

• Diagnostic phase: a very small catheter is endoscopically guided through the ampulla of Vater into the common bile duct. A small amount of contrast material is then injected, and x-rays are taken. This dye outlines the bile duct and the pancreatic duct, and shows the site and the morphology of biliary blockage that might be due to cholangiocarcinoma.
• Operative phase: a small cut is made on the ampullary orifice (papillotomy), then the stent is passed through the endoscope and is placed into the bile duct. The stent helps keep the common bile duct open and resists compression from the surrounding cancer.

Cross-sectional imaging confirms the diagnosis and is necessary to stage the neoplasm. A staging system is a standardized way in which the cancer care team describes the extent that a cancer has spread, and contains different pieces of information, including:

• The size of the primary tumor
• Whether the tumor has spread to nearby organs or vessels
• Whether the tumor has spread to nearby lymph nodes
• Whether the tumor has spread (metastasized) to distant organs 

The diagnostic work-up of distal cholangiocarcinoma is similar to that of pancreatic ductal adenocarcinoma. Here are outlined the imaging test commonly used:

• Contrast-enhanced computed tomography (CT). The CT scan is an x-ray test (it uses ionizing radiations) that produces detailed cross-sectional images of the body. 3D reconstruction softwares allow detailed tumor characterization. CT scans show the common bile duct and the pancreas fairly clearly and often can confirm the location of the tumor, CT scans can also show the nearby organs, as well as lymph nodes and distant organs where the cancer might have spread. 

• Magnetic resonance imaging (MRI). MRI scan use radio waves and strong magnets instead of x-rays. It is a multiplanar imaging modality. MRI with cholangio-pancreatography is very useful to outline the biliary system anatomy and common bile duct stricture morphology. 

• Ecoendoscopic ultrasound (EUS). Endoscopic ultrasound is performed using an ultrasound probe that is attached on the tip of an endoscope. This allows direct vision of the duodenum and of the papillary region as well as a very detailed ultrasonography of the pancreas and intra-pancreatic common bile duct. It is probably better than CT scan for spotting neoplastic thickening of the common bile duct wal. If a tumor is seen, a trans-gastric or a trans-duodenal biopsy can be performed during this procedure. 

• Positron-emission tomography (PET). PET-scan involves the use of a very small dose of a intravenous radiotracer (known as 18-fluorodeoxyglucose or FDG). Neoplastic cells absorb large amount of FDG, which is detected by the scanner. These functional images have however insufficient spatial resolution; hence PET-scan is combined with CT-scan (PET-CT) to provide detailed images of the primary tumor. PET-CT may be especially useful for spotting cancer that has spread beyond the common bile duct and nearby organs.  

Although spatial resolution of cross-sectional imaging modalities has improved, it may be difficult to distinguish between a distal cholangiocarcinoma (intrapancreatic bile duct) and a ductal adenocarcinoma of the pancreatic head. The latter cancer type may infiltrate diffusely the common bile duct, such that it is not possible to establish where the tumor has arisen from. 

The principal tumor marker measured in pancreatobiliary neoplasms is Ca 19.9, an antigen released by neoplastic cells. Ca 19.9 serum levels are elevated in many patients with distal cholangiocarcinoma. However, there are also some non-cancerous conditions that cause a high level of Ca 19.9, such as gallstones, pancreatitis, cystic fibrosis, liver disease, pulmonary and thyroid diseases. Furhermore, Ca 19.9 can be elevated in people with obstruction of the bile ducts, that is the case of many patients with cholangiocarcinoma. On the contrary, in patients who lack the Lewis antigen (a blood type protein on red blood cells), which is about 10% of the Caucasian population, Ca19.9 is not expressed, even in those with large tumors. That’s why Ca 19.9 is not particularly useful as a diagnostic test for pancreatobiliary neoplasms. After the diagnosis of cholangiocarcinoma is confirmed, and if the individual’s Ca 19.9 level was elevated before treatment, the Ca 19.9 test can be used as a prognostic factor.

Once the radiologic characterization has been obtained (tumor size, relation with peripancreatic vessels, lymph node status, presence of metastases), this information is combined to assign a stage. The current staging is based on the TNM system (tumor/node/metastasis), according to the American Joint Commitee on Cancer (AJCC, www.cancerstaging.org). Tumor stage is expressed in Roman numerals I through IV. Here are the AJCC stage groups of for extra-hepatic cholangiocarcinoma (seventh edition, 2010):

• Stage 0: The tumor is confined within the inner layer of the biliary duct. 
• Stage IA: The tumor is confined within the wall of the biliary duct. 
• Stage IB: The tumor is growing outside the bile duct. It has not spread to nearby lymph nodes or distant sites. 
• Stage IIA: The tumor has spread to nearby organs (pancreas, gallbladder, liver). It has not spread to nearby lymph nodes or distant sites. 
• Stage IIB: The tumor is either confined to the bile duct or is growing outside the bile duct, but tt has spread to nearby lymph nodes. The tumor has not spread to distant sites. 
• Stage III: The tumor is growing outside the bile duct into major blood vessels. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.
• Stage IV: The cancer has spread to distant sites.

Radiologic staging divides distal cholangiocarcinoma into groups based on whether or not it is likely it can be removed surgically:

• Resectable neoplasm
• Locally advanced neoplasm
• Metastatic neoplasm

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