Can image-enhanced cholangioscopy distinguish benign from malignant lesions in the biliary duct?

A new video peroral cholangioscopy (POCS) has been developed with high-quality digital imaging, and its clinical use has been reported. Additionally, direct peroral cholangioscopy (D-POCS) using an ultraslim endoscope has been proposed recently. To improve the diagnostic yield of POCS or D-POCS, image-enhanced endoscopy has been used in combination. Chromoendoscopy with methylene blue staining (ME), autofluorescence imaging (AFI), and narrow-band imaging (NBI) has been evaluated in biliary tract diseases. Observation of the mucosal structure and vessels is reportedly important for distinguishing non-neoplasms from neoplasms. Therefore, NBI is the most promising tool among image-enhanced endoscopies as it can enhance visualization of the mucosal structure and vessels simultaneously. There are currently few reports that have evaluated the utility of POCS or D-POCS based on pathological findings. Thus, endoscopic findings of the bile duct mucosa have not yet been fully established. At present, POCS-guided biopsy should be carried out.