[A case of non-invasive IPMC with fibrotic lesion-like "tubular complex"].

A 73-year-old man was incidentally diagnosed with a cystic lesion in the pancreatic body. Ultrasonography, abdominal computed tomography, magnetic resonance imaging, endoscopic retrograde cholangiopancreatography, and endoscopic ultrasound were performed, and a nodule was detected in the cystic lesion along with an irregularity of the main pancreatic duct. An initial diagnosis of a mixed-type intraductal papillary mucinous neoplasm was made, and a central pancreatectomy was performed. However, the final diagnosis was altered to non-invasive intraductal papillary mucinous carcinoma (IPMC). The histopathological examination revealed a fibrotic lesion that was similar to "tubular complex" findings observed in mouse models of pancreatic cancer. The fibrotic lesion was placed between the main pancreatic duct lesion and branch-duct cystic lesion. The changes reflected in branch-level stenosis may be caused by IPMC growth.