Sensitivity Of Cytology And Immunohistochemistry For Diagnosis Of Pancreaticobiliary Cancer

TPS490 Background: Biliary strictures present a diagnostic challenge to differentiate benign disease from hepatopancreaticobiliary (HPB) malignancies. ERCP cytology is commonly performed in these patients; however, its sensitivity for diagnosis of HPB malignancy is poor (41.6%). Many adjunctive tests have been investigated to improve the sensitivity of HPB biopsies. In a recent meta-analysis by our group the best immunohistochemical (IHC) stains were a combination of IMP3, S100A4, and standard cytology. IHC stains for S100P and pVHL negativity were also helpful. Based on this meta-analysis we have designed a retrospective analysis of old cell block specimens to demonstrate the sensitivity and specificity of a combination IHC staining panel in detecting HPB maliganancies. Methods: Retrospective IHC staining will be carried out on old cell blocks from ERCP brushings and EUS-FNA. Expression of IMP3, S100A4, S100P, and pVHL will be determined. Using this panel as a combination we will determine its sensitivity and specificity on 200 patient samples. We will further determine how many stains are necessary to achieve maximum sensitivity by subtraction of data from one or more IHC stains followed by repeating sensitivity calculations. Finally, we will calculate the cost of conducting these tests and determine the cost-benefit ratio of employing these tests in the wider clinical setting. Conclusions: Overall we feel these studies will advance the precision with which clinicians can determine the presence of HPB malignancy in patients undergoing biopsy. This will ultimately lead to fewer patients with benign disease undergoing resection unnecessarily.