A Case of Adipophilin-Positive Pancreatic Intraductal Papillary Mucinous Neoplasm (IPMN) With Eosinophilia.

Adipophilin expression and eosinophilia associated with intraductal papillary mucinous neoplasm (IPMN) are extremely rare in the literature, and the relationship between adipophilin expression and IPMN remains unclear. This study reports the case of a 67-year-old male patient with adipophilin-positive IPMN and eosinophilia, which diminished following R0 surgical resection. The patient underwent pancreaticoduodenectomy for a pancreatic head (Ph) tumor detected by abdominal echo screening. Computed tomography revealed a polycystic mass approximately 40 mm in diameter. The resected specimen was located in the Ph and measured 35 × 31 × 20 mm (TS2). Histopathological examination revealed an IPMN, low-grade papillary growth, and a branch duct type. Immunohistochemically, mucin 5AC (MUC5AC) and MUC6 were expressed in the tumor cytoplasm, classifying it as the gastric type. In addition, eosinophil infiltration was observed in the glandular ducts of the tumor, and adipophilin was expressed in the tumor cytoplasm. This case highlights the rare coexistence of adipophilin expression and eosinophilia in IPMN, necessitating further investigation.