Summary

A 74-year-old woman with multiple cystic lesions in the pancreas was first examined at a previous hospital. Many of the lesions in the head and body were diagnosed as a branch duct intraductal papillary mucinous neoplasms (IPMN), but one lesion in the tail was a simple cyst. She had no surgical treatment because there were no signs of malignancy in any of the lesions. After 3 years, solid components appeared only in the tail lesion. Because of its preoperative diagnosis as a mucinous cystic neoplasm (MCN), distal pancreatectomy was performed. Histopathological findings revealed that the cystic tumour in the tail was IPMN with minimally invasive carcinoma and the other lesion in the body was IPMN with low-grade dysplasia. They were IPMNs bridged by a non-dilated main pancreatic duct. There may be some cases in which it is difficult to diagnose between IPMN and MCN.