A study to improve the identification of pancreatobiliary adenocarcinoma utilizing fine-needle aspiration cytology and immunohistochemical application for KOC and S100P

IntroductionThe identification of pancreatic adenocarcinoma by fine-needle aspiration (FNA) cytology is a difficult, yet critical, task. This study uses a panel of two immunohistochemical (IHC) markers, KOC and S100P, to augment the interpretation of pancreatic adenocarcinoma using cytopathology specimens and to compare these to corresponding surgical specimens.Materials and methodsWe retrospectively reviewed 33 surgical specimens with pancreatic adenocarcinoma and 33 corresponding, preceding FNA cytology specimens. IHC studies for KOC and S100P were performed on both the surgical specimens and cytology cell blocks. Three pathologists reviewed the staining intensity and amount of tumor cell staining within these blocks. The findings were then analyzed for sensitivity, specificity, and combined sensitivity and specificity for the 2 markers.ResultsKOC performed similarly to S100P in sensitivity for surgical specimens (90.9% for both) and better for FNA specimens (92.3% versus 82.7%, respectively). The specificity of KOC was significantly better than S100P for surgical and FNA specimens (100% for KOC in both specimens versus 72.7% and 89.7% for S100P in both specimens, respectively). The combined sensitivity of the panel of KOC and S100P was 99.2% for surgical specimens and 98.7% for FNA specimens. The combined specificity was 72.7% for surgical specimens and 89.7% for FNA specimens.ConclusionsWe found using KOC and S100P on FNA cell block cytology specimens to be a useful adjunct for interpretation when an interpretation of atypical or suspicious for pancreatic ductal adenocarcinoma is being considered and there are atypical epithelial cell groups in the cell block.