AbstractWe report a case of intracystic papillary neoplasms (ICPN) that was difficult to differentiate from adenocarcinoma of the gallbladder. A 64-year-old man visited our hospital for an examination of gallbladder tumors. At the preoperative examination, the tumor was revealed a papillary type of tumor in the body of the gallbladder without the findings that without the findings that suggested the tumor invasion into the deep subserosal layer. The patient underwent an extended cholecystectomy. Papillary lesions were observed mainly in the body of the gallbladder, with flattened elevated lesions at the gallbladder fundus. Within each of these tumors, cells corresponding to intraepithelial adenocarcinoma were irregularly interspersed, leading to a diagnosis of ICPN. The patient is currently undergoing follow-up with no recurrence postoperatively. The prognosis of ICPN is generally good; however, preoperative diagnosis remains challenging. Therefore, a treatment plan for gallbladder cancer should be applied.