Objective: CD117/KIT overexpression is common in neoplasms such as gastrointestinal stromal tumors and predicts clinical response to tyrosine kinase inhibitors. Pancreatic adenocarcinoma has a poor prognosis, and therefore, targeted molecular therapy may be beneficial. Marked differences in the incidence of CD117/KIT expression have been reported in pancreatic adenocarcinoma. The aim of this study was to test the hypothesis that CD117/KIT expression is unusual in pancreatic adenocarcinoma.
Methods: CD117/KIT immunohistochemistry was performed on 23 archival pancreatic adenocarcinoma samples using 2 primary antibodies.
Results: Satisfactory internal and external positive control labeling was achieved for both primary antibodies. No tumor cell labeling was identified using one primary antibody, whereas all cases showed cytoplasmic CD117/KIT staining with the second. However, CD117/KIT expression was also identified using the latter within nuclei and benign pancreatic epithelium, suggesting that artifactual staining was occurring.
Conclusions: Pancreatic adenocarcinoma does not express CD117/KIT as assessed using the primary immunohistochemical antibody usually used in our laboratory for CD117/KIT detection. The variation in reported incidence of CD117/KIT expression in pancreatic adenocarcinoma is because of methodological differences in immunohistochemical technique. Ideally, immunohistochemical studies of this molecule should be combined with mutational status testing of the c-kit gene.