A 74-year-old man with an expanding pancreatic cyst was referred to our hospital for the purpose of close examination and treatment. Contrast-enhanced computed tomography revealed a 9-mm dilated main pancreatic duct and a multilocular cystic lesion with communication with the main pancreatic duct at the pancreatic head. Endoscopic ultrasonography revealed no apparent neoplastic lesions inside. No apparent neoplastic lesion was found on endoscopic retrograde cholangiopancreatography and pancreaticoscopy. The patient was considered to be a branched intraductal papillary mucinous neoplasm (IPMN) with dilatation of the main pancreatic duct. Although the type of IPMN is sometimes difficult to determine, we could classify the type using pancreaticoscopy.
