Expression of maspin in pancreatic neoplasms: Application of maspin immunohistochemistry to the differential diagnosis

Maspin is a unique member of the serpin family, which inhibits tumor invasion and metastasis of the human breast and prostate cancers. Immunohistochemical evaluation of the maspin expression in pancreatic neoplasms has never been performed. The authors examined the expression of maspin in various pancreatic neoplasms to investigate its usefulness as an adjunct diagnostic marker. Formalin-fixed, paraffin-embedded tissue sections from 107 pancreatic neoplasms were immunostained with anti-maspin antibody using an EnVision+ System. Maspin was expressed in all ductal adenocarcinomas, of which 78.9% (30/38) were high expressors and 21.1% (8/38) were low expressors. All 13 intraductal papillary mucinous tumors and 11 of the 13 mucinous cystic tumors reacted to maspin with stronger expressions in carcinomatous lesions. In contrast, acinar cell carcinoma, pancreatic endocrine tumors, solid-pseudopapillary tumors, and serous cystadenomas demonstrated no maspin expression. In addition, nonneoplastic pancreatic parenchyma and chronic pancreatitis lacked expression. The current study suggests that maspin may be of importance in the pathobiology of pancreatic neoplasms with epithelial origin, especially pancreatic tumors that are composed of mucin-producing cells. It may be useful in separating ductal adenocarcinoma from acinar cell carcinoma, pancreatic endocrine tumor, solid-pseudopapillary tumor, and chronic pancreatitis, especially in needle biopsy specimens.