Mixed-type intraductal papillary mucinous neoplasm with oncocytic and signet-ring features: a case report

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are cystic epithelial tumors with variable malignant potential. Mixed-type IPMNs, which involve both the main pancreatic duct (MPD) and branch ducts, are associated with a greater risk of high-grade dysplasia and invasive carcinoma. Intraductal oncocytic papillary neoplasm (IOPN) is a rare histologic subtype. The coexistence of multifocal IOPN and signet-ring cell carcinoma within a mixed-type IPMN is exceptionally rare. A 42-year-old woman from southern Iran, presented in March 2025 with vague epigastric discomfort and weight loss. Cross-sectional imaging demonstrated diffuse dilation of the main pancreatic duct with enhancing mural nodules and a branch-duct cystic lesion in the pancreatic tail. Total pancreatectomy with splenectomy was performed. Histopathological examination revealed mixed-type IPMN with multifocal oncocytic architecture and invasive signet-ring cell carcinoma arising in an intestinal-type component. Ten of 34 resected lymph nodes contained metastatic carcinoma. The postoperative course was uneventful, and no recurrence was detected during six months of follow-up. This case highlights the aggressive potential of mixed-type IPMN with oncocytic and signet-ring cell features. Comprehensive imaging assessment and timely surgical resection are essential for achieving optimal oncologic outcomes.