Endoscopic Diagnosis of Cholangiocarcinoma

Abstract

Cholangiocarcinoma (CCA) is a group of malignancies that arise from the epithelial cells of the bile ducts. Patients with CCA can be asymptomatic until the disease is in its advanced stage. Although noninvasive imaging remains the first step in the diagnosis of CCA, endoscopy is considered indispensable. Conventional endoscopic methods of tissue acquisition include brush cytology and fluoroscopy-guided intraductal biopsies that are obtained through endoscopic retrograde cholangiopancreatography (ERCP). The addition of fluorescence in situ hybridization (FISH) testing to routine cytology is also widely used. Overall, these methods have a low diagnostic yield and remain suboptimal, often leaving the patient with the unsatisfactory diagnosis of indeterminate biliary strictures. Endoscopic ultrasound (EUS) and peroral cholangioscopy (POC) have emerged as adjunct modalities in the evaluation of indeterminate biliary strictures and CCA. Evolving genetic and molecular diagnostic applications, such as next-generation sequencing (NGS) and exosomal RNA analysis, have also shown promising improvement. Other evolving technologies that can provide additional diagnostic value but may not be clinically feasible include probe-based confocal laser endomicroscopy (pCLE) and optical coherence tomography. In this review, the role of EUS, POC, pCLE and optical coherence tomography in the diagnosis of CCA will be discussed along with the diagnostic yield of brushing and intraductal biopsy. New emerging diagnostic techniques of endoscopically obtained samples will be evaluated as well.