Post written by Il Sang Shin, MD, PhD, Jong Ho Moon, MD, PhD, and Yun Nah Lee, MD, PhD, from the Digestive Disease Center and Research Institute, Department of Internal Medicine, SoonChunHyang University School of Medicine, Bucheon, Cheonan, and Seoul, Korea.

Indirect diagnostic modalities such as CT, magnetic resonance imaging, and ERCP are sometimes unsatisfactory for detecting intraductal neoplasms of the bile duct (IN-Bs), which peroral cholangioscopy (POC) can detect.

Direct POC using an ultraslim endoscope, an established POC system, enables optimal diagnosis of various biliary tract diseases with high-quality endoscopic imaging. It also yields specific features of the surface structure and microvascular pattern with the capability of image-enhanced endoscopies such as narrow-band imaging (NBI).

Although efforts have been made to classify the visual findings to predict malignancy, experience in the interpretation of visual findings is limited. Therefore, we investigated the POC findings of IN-Bs and created a reliable endoscopic classification system using POC with NBI based on surface structure and microvascular architecture.

Direct POC was technically successful in 458 of 471 patients (97.2%). Of those patients, 131 (27.8%) showed intraductal superficial lesions of the bile duct (ISL-Bs). The technical success rate of POC-guided forceps biopsy sampling (POC-FB) for ISL-Bs was 94.7% (124/131 patients). The pathologic diagnoses after POC-FB for patients with ISL-Bs included IN-Bs in 54 patients (43.5%), and curative surgical resections were performed in 21 (38.9%). Papillary lesions, nodular lesions, and irregularly and regularly dilated and tortuous vessels were significantly associated with IN-Bs (P < .05). The area under the receiver-operating characteristic curve of our classification system was .899.

In our study, POC with NBI was useful for the detection of IN-Bs, and our novel classification system based on both the surface structure and microvascular pattern allowed efficient differentiation of IN-Bs from ISL-Bs. The results of our study are important because reliable detection, characterization, and pathologic confirmation of ISL-Bs can promote early detection of IN-Bs in real clinical practice.

Further studies on the histopathology of POC findings may enhance verification of the predictive accuracy of our novel endoscopic classification system.

Proposed endoscopic classification system for intraductal superficial lesion of the bile duct, including intraductal neoplasm of the bile duct, according to surface structure and microvascular pattern. POC, Peroral cholangioscopy; NBI, narrow-band imaging.

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