[644] Utility and Limitations of Mesothelin Immunohistochemistry for Pancreatic Neoplasia in Both Surgical and Fine Needle Aspiration Materials

JP Glass, RE Donohue, LA Cerilli. University of New Mexico, Albuquerque, NM

Background: Previous studies have shown that mesothelin overexpression can be detected by immunohistochemistry in pancreatic adenocarcinoma. Our study attempts to confirm these results and further characterize immunohistochemical mesothelin staining in both fine needle aspirates and surgical materials from a spectrum of pancreatic neoplasms.
Design: Immunohistochemical staining for mesothelin was performed on resection or biopsy specimens from: 23 ductal adenocarcinomas, 15 ampullary adenocarcinomas, 4 distal common bile duct adenocarcinomas, 6 mucinous neoplasms, 3 serous cystadenomas, 4 benign cysts, 1 solid pseudopapillary tumor, and 2 chronic pancreatitis cases. Mesothelin staining was also performed on cell block material from 37 fine needle aspirates of pancreatic adenocarcinoma. Positive staining in the surgicals was defined as at least 2+ (moderate intensity) apical staining in at least 5% of cells. Positive staining in the aspirations was defined as any adenocarcinoma cells with at least 2+ apical staining.
Results: 24 of 42 resected or biopsied adenocarcinomas (ductal, ampullary, and distal common bile duct) stained for mesothelin, while none of the non-carcinoma cases (0 of 16) showed positive staining (p = 0.0000784). In addition, only 3 of the 15 ampullary adenocarcinomas were positive for mesothelin, compared with 21 of 27 of the non-ampullary adenocarcinomas (p = 0.0002884). 27 of the 37 pancreatic adenocarcinoma fine needle aspirates were also positive for mesothelin. Of the 10 negative cases, limited material was present for evaluation in 3 cases (30%).

TOTALMESOTHELIN +MESOTHELIN -
ALL ADENOCARCINOMA422418
PANCREATIC DUCTAL ADENOCARCINOMA23185
AMPULLARY ADENOCARCINOMA15312
BILIARY (BILE DUCT) ADENOCARCINOMA431
ALL MUCINOUS NEOPLASMS606
INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM404
MUCINOUS CYSTIC NEOPLASM202
SEROUS CYSTADENOMA303
SOLID-PSEUDOPAPILLARY NEOPLASM101
CHRONIC PANCREATITIS202
SIMPLE CYST OR PSEUDOCYST404
FINE NEEDLE ASPIRATIONS OF PANCREATIC ADENOCARCINOMA372710



Conclusions: This study confirms that mesothelin expression in pancreatic adenocarcinoma can be detected by immunohistochemistry in both surgical and fine needle aspiration specimens. In addition, this study supports the novel finding that adenocarcinoma arising from the ampulla of Vater does not usually express mesothelin and further suggests that mesothelin is not expressed by other pancreatic neoplasms, such as pancreatic mucinous neoplasms.
Category: Gastrointestinal

Monday, March 22, 2010 1:00 PM

Poster Session II # 88, Monday Afternoon

 

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