摘要： A 79-year-old man was referred to our hospital because of jaundice. He had previously undergone Billroth-II gastrectomy for gastric cancer. Contrast CT showed a mass lesion in the pancreatic head with contrast effects and invasion of the distal bile ducts. Additionally, ERCP was performed to obtain more detail. Because of the patient’s prior gastrectomy, ERCP was performed with a short-type single-balloon enteroscope, SIF-H290S (Olympus Medical Systems, Tokyo, Japan) with a working length of 152 cm and channel diameter of 3.2 mm. Cholangiography showed a defect in the distal bile duct. The procedure was then completed with fluoroscopy-guided biopsy of the bile duct. However, the size of the biopsy sample was insufficient to enable a conclusive diagnosis. ERCP was performed again 2 weeks later. With the aim of improving diagnostic ability, a CF-H260AI colonoscope (Olympus Medical Systems Corporation, Tokyo, Japan) with a working length of 133 cm and channel diameter of 3.7 mm was used to perform peroral cholangioscopy (POCS) guided by SpyGlass DS (Boston Scientific Corp, Marlborough, Mass, USA) fluorescein-dripping laser endomicroscopy (pCLE) probe-based confocal (CholangioFlex, Cellvizio; Mauna Kea Technologies, Inc, Paris, France) and POCS-guided biopsy. When the papilla was reached, it was possible to insert the cholangioscope inside the bile duct. Both findings suggested cancer, with POCS showing an irregular, hemorrhagic, papillary protrusion lesion, and pCLE showing a dark ductal structure with irregular margins. POCS confirmed that the bile ducts at nonlesion sites had normal mucosa, and pCLE showed a reticular network of thin, dark, branching bands, considered to be normal. POCS-guided biopsies were performed at both lesion and nonlesion sites. In contrast to the initial fluoroscopy-guided biopsy performed with ERCP, a sample of sufficient size was collected by the POCS-guided biopsy. The biopsy samples contained atypical cells with hyperchromatic nuclei and eosinophilic cytoplasm. Similarly to the pCLE findings, these formed a ductal structure with irregular margins. The nuclei showed marked variations in size, irregular morphology, and irregular arrangement, indicating adenocarcinoma. Biopsy specimens from normal bile ducts showed no malignancy. Therefore, a preoperative diagnosis of pancreatic cancer was made, and pancreatoduodenectomy was performed. The histopathologic findings from the surgical samples were similar to those from the POCS biopsy tissue samples, and irregular, invasive proliferation by atypical bile ducts with eosinophilic cytoplasm was found, confirming pancreatic cancer.