Endoscopic Retrograde Cholangiopancreatography-guided Tissue Acquisition for Extrahepatic Cholangiocarcinoma

Cholangiocarcinoma is a heterogeneous malignancy of the biliary epithelium.It is anatomically classified into intrahepatic, perihilar, and distal subtypes.Extrahepatic cholangiocarcinoma, encompassing perihilar and distal cholangiocarcinomas, commonly presents as a biliary stricture and generally requires histological confirmation before definitive treatment planning.However, making an accurate tissue diagnosis remains challenging because of the tumor's desmoplastic nature, submucosal and periductal growth pattern, and the anatomical difficulty of accessing the bile duct.Endoscopic retrograde cholangiopancreatography (ERCP)-guided tissue acquisition has traditionally relied on brush cytology and fluoroscopy-guided forceps biopsy.The diagnostic sensitivity of brush cytology is relatively low although the method is simple and safe.Accumulating evidence suggests that forceps biopsy provides a higher diagnostic yield in patients with suspected cholangiocarcinoma, particularly when an adequate number of tissue fragments is obtained.Technical optimization, including appropriate forceps selection, sufficient tissue sampling, balloon dilation before biopsy, and adjunctive device use, may further improve diagnostic performance.Ancillary tests, such as fluorescence in situ hybridization, molecular profiling, and next-generation sequencing, can complement cytology in selected cases, while their routine clinical use depends on institutional availability and standardization.Alternative approaches, including percutaneous transhepatic cholangiography-guided biopsy, endoscopic ultrasound-guided tissue acquisition, and cholangioscopy-guided biopsy, may be considered according to stricture location, suspected etiology, and local expertise when ERCPguided tissue acquisition is unsuccessful or anatomically limited.A stepwise and individualized diagnostic strategy integrating imaging findings, stricture characteristics, tumor morphology, and procedural feasibility is essential for optimizing tissue diagnosis in patients with extrahepatic cholangiocarcinoma.