A case report of intracholecystic papillary neoplasm of the gallbladder resembling a submucosal tumor

BACKGROUND: Intracholecystic papillary neoplasm (ICPN) is defined as papillary tumors detected macroscopically in the gallbladder. We report a case of ICPN which exhibited the atypical form like a submucosal tumor. CASE PRESENTATION: A 70-year-old man was admitted to our hospital because of hepatic disorder. Computed tomography and magnetic resonance imaging showed irregular thickening of the wall within the gallbladder fundus. Because the lesion might have been malignant, we performed laparoscopic cholecystectomy and liver bed resection. Macroscopic findings showed the mucosal surface of the tumor was smooth, and its form was similar to that of a submucosal tumor. Histopathological examination revealed papillary tumors within the mass with low-grade dysplasia; therefore, we diagnosed ICPN. CONCLUSION: In the present case, ICPN was resembling a submucosal tumor macroscopically because the tumors arose into the Rokitansky-Aschoff sinus and the adenomyomatous hyperplasia was merged with the ICPN. It is necessary to consider the possibility of tumor lesions within adenomyomatous hyperplasia.