[633] Immunohistochemical Study of Ampullary and Small Bowel Adenocarcinomas

Rongjun Guo, Asif Rashid, Michael Overman, Hua Wang, James Abbruzzese, Huamin Wang. UT MD Anderson Cancer Center, Houston, TX

Background: Multiple types of epithelium including duodenal, pancreatic duct and common bile duct epithelium meet within the ampulla of Vater. The exact epithelial origin for ampullary adenocarcinoma (AA) is not known. The aim of this study is to compare the immunohistochemical profile between the AAs and primary small bowel adenocarcinomas (SBAs).
Design: We retrospectively reviewed 50 archival cases of SBA and 116 cases of AA that were diagnosed at our institution. The tissue microarrays were constructed using the formalin-fixed paraffin embedded tissue with two 1.0 mm cores from representative areas of each tumor. A panel of four markers, including P53, CyclinD1, BCL2 and P21 were examined by immunohistochemistry. The immunohistochemical staining results from the AAs and SBAs were compared using Chi-square analysis.
Results: Of the 50 cases of SBA, 32 cases (64%) were positive for cyclin D1, which was significant lower than 79% (92/116) in AAs (P<0.04). P21 and BCL-2 are positive in 12% (6/50) and 12% (6/50) of SBAs respectively, compared to 41% (48/116) and 0% (0/116) of AAs (p=0.0002 and p=0.001 respectively). However we did not observe significant difference between SBAs and AAs in the expression of p53 [60% (30/50) in SBAs vs 51% (59/116), p=0.30].
Conclusions: Our study indicated that AAs are immunophenotypically different from SBAs.
Category: Gastrointestinal

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 110, Tuesday Afternoon


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