A case of carcinoma in situ of the pancreas concomitant with branch duct intraductal papillary mucinous neoplasm

Abstract

A 63 year-old woman presented with a cystic lesion in the pancreatic head and main pancreatic duct dilatation by abdominal ultrasonography. A cystic lesion with size of 30mm and dilatation of the main pancreatic duct (6mm) in the pancreatic body were revealed with MRCP. No cyst wall thickening or mural nodule was observed during EUS. There was no mass lesion resulting in stenosis of the main pancreatic duct. ERP showed localized stenosis of the main pancreatic duct at the head and the cytodiagnosis of the pancreatic juice was Class V. We diagnosed the stenosis as carcinoma in situ (CIS) concomitant with IPMN, therefore pylorus-preserving pancreatoduodenectomy was performed. Histopathological examination revealed CIS (20mm) in the main pancreatic duct at the head, and the cystic lesion contained no nodules diagnosed as non-invasive IPMC (gastric type). Although IPMC was in proximity to CIS, continuity between them was not apparent. Since discrimination between invasive carcinoma derived from IPMN and concurrent pancreatic cancer was assumed to be difficult, we considered that this case could have provided an invaluable finding to capture the precursor lesions to each cancer.