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Mesothelin Is Overexpressed in Pancreaticobiliary Adenocarcinomas but Not in Normal Pancreas and Chronic Pancreatitis

Raffit Hassan MD, Zoltan G. Laszik MD, PhD, Megan Lerner, Mark Raffeld MD, Russell Postier MD, Daniel Brackett
DOI: http://dx.doi.org/10.1309/F1B64CL7H8VJKEAF 838-845 First published online: 1 December 2005


Mesothelin, a cell surface glycoprotein present on normal mesothelial cells, has been reported to be expressed in pancreatic adenocarcinomas. We conducted this study to fully characterize mesothelin expression in surgically resected, formalin-fixed, paraffin-embedded tissue specimens of 18 pancreatic adenocarcinomas, 9 adenocarcinomas of the ampulla of Vater, 12 adenocarcinomas of the common bile duct, and 17 cases of chronic pancreatitis. Mesothelin immunostaining was performed using the antimesothelin monoclonal antibody 5B2. All 18 cases (100%) of pancreatic adenocarcinomas showed mesothelin expression, as did 8 (89%) of 9 cases of ampullar adenocarcinoma and all 12 cases (100%) of common bile duct adenocarcinoma. In all cases of pancreaticobiliary adenocarcinoma, the adjacent normal pancreas did not stain for mesothelin. Of 17 specimens of chronic pancreatitis, 16 were negative for mesothelin expression, and 1 case showed weak mesothelin staining of fewer than 5% of normal pancreatic ducts. Our results demonstrated mesothelin expression in the majority of pancreaticobiliary adenocarcinomas and no expression in normal pancreatic tissues and in chronic pancreatitis.

Key Words:
  • Mesothelin
  • Pancreatic, ampullar, and common bile duct cancer
  • Chronic pancreatitis
  • Immunohistochemistry