Fig. 1. Peroral cholangioscopy findings using texture and color enhancement imaging (TXI). (A) White light imaging. A protruded lesion is observed. (B) TXI imaging. TXI showing the structural change clearer than white light imaging.

Fig. 2. Peroral cholangioscopy findings. (A, B) A case of cholangiocarcinoma. Irregular surface in the mucosa and tortuous, dilated vessels are observed. (C, D) A case of benign biliary stricture. Smooth mucosa without vascular proliferation and well-organized granular mucosa with low height, without papillary tumors, are observed.

Fig. 3. Peroral cholangioscopy-guided biopsy is performed on an indeterminate biliary stricture with dedicated forceps; open forceps (A) and closed (B).

Fig. 4. Probe-based confocal laser endomicroscopy (pCLE) under the direct view of peroral cholangioscopy (POCS). (A) Cholangiogram showing the hilar biliary stricture (arrow). (B, C) pCLE under the direct view of POCS is performed. Probe is attached to the lesion under POCS. (D) pCLE findings. Dark clumps (arrow) indicating malignancy is observed.

Fig. 5. A case of large and multiple bile duct stones. (A) Cholangiography showing large and multiple bile duct stones. (B, C) Peroral cholangioscopy-guided electrohydraulic lithotripsy is performed to fragment the stones. (D) Complete stone extraction is achieved.