Intracholecystic papillary-tubular neoplasm diagnosed by peroral cholangioscopy.

Intracholecystic papillary-tubular neoplasm (ICPN) is a preinvasive neoplasm arising from the gallbladder mucosa, with a better prognosis than conventional gallbladder carcinoma; however, accurate preoperative differentiation based solely on imaging remains challenging. When complicated by infection, inflammatory changes often mimic tumor invasion, making it difficult to accurately evaluate the tumor extent. We report the case of an 83-year-old male with a liver abscess and suspected advanced gallbladder carcinoma. Initial imaging suggested invasion of the liver and right hepatic artery, and the tumor was initially considered unresectable given the advanced age of the patient and reduced activities of daily living. However, imaging after infection control suggested limited invasion. During endoscopic management of cholangitis, we successfully advanced the cholangioscope into the gallbladder. Direct observation revealed that the interior of the gallbladder was filled with a papillary tumor. Biopsy findings supported the diagnosis of ICPN. Surgery was performed subsequently, achieving complete resection. Pathological examination revealed that the invasion was confined to the mucosa (pT1a). This case suggests that infection control may be essential for evaluating the tumor extent. The case also suggests that peroral cholangioscopy is valuable in the diagnosis of ICPN.