Role of Endoscopic Ultrasonography in the Evaluation of Extrahepatic Cholangiocarcinoma

Cholangiocarcinoma is a malignancy that arises from biliary epithelium and is associated with a poor prognosis. Accurate preopera­tive diagnosis and staging of cholangiocarcinoma continues to remain difficult. Endoscopic retrograde cholangiopancreatography (ERCP) is the most commonly performed procedure for cholangiocarcinoma and can provide a tissue diagnosis through brush cytology of the bile duct. However, the sensitivity of biliary brush cytology to diagnose cholangiocarcinoma may be as low as 30%. Endoscopic ultrasound (EUS) is a diagnostic modality which may overcome the limitations of other imaging and biopsy techniques in this setting. EUS can complement the role of ERCP and provide a tissue diagnosis through fine needle aspiration (FNA) and staging through ultrasound imaging. There is currently a paucity of data about the exact role of EUS for the diagnosis of cholan­giocarcinoma in patients with indeterminate extrahepatic biliary strictures. Although multiple studies have shown that EUS is more accurate than ERCP and radiologic imaging for identifying a biliary mass and diagnosing cholangiocarcinoma, the sensitivities are variable. More importantly, the incidence of false negative results is not negligible, though the specificity is close to 100%. There is also controversy regarding the role of EUS-FNA, since even though this may increase diagnosis, it can also lead to tumor seeding.