Addition of analysis of KRAS mutation or immunohistochemistry with MUC1 and carcinoembryonic antigen improves the diagnostic performance of fine needle aspiration cytology for the diagnosis of pancreatic carcinoma

Background Pancreatic adenocarcinoma (PAC) is a health problem because of high lethality, increasing incidence and the absence of an early diagnosis. Biopsy by fine needle aspiration guided by endoscopic ultrasound has allowed obtaining tissue for cytopathological analysis, but there are several problems with their interpretation. We aimed to compare the diagnostic performance of the cytopathological analysis with the addition of either an immunohistochemical (IHC) panel or the KRAS mutation for the diagnosis of PAC. Methods We evaluated 62 pancreatic lesions by fine needle aspiration guided by endoscopic ultrasound, applying an IHC panel with mucin (MUC)-1, MUC4, carcinoembryonic antigen (CEA) and p53. All cases also had a KRAS mutation determination. Three cytopathologists blinded to clinical data and the KRAS status reviewed the cytology independently. We calculated diagnostic performances for the cytology alone, cytology+IHC and cytology+KRAS to show the best method to diagnose PAC. Results From 62 samples, 50 (80.6%) were PAC and 12 benign lesions. The cytopathological analysis correctly interpreted 26 malignant and 12 non-neoplastic cases (sensitivity 52%, specificity 100% and diagnostic accuracy 61.3%). The KRAS mutation was present in 88% of PAC. The cytology+ KRAS mutation increased the sensitivity by 10% and the diagnostic accuracy by 8%. The sensitivity increased by 2% adding either MUC1 or CEA to the cytology, and the diagnostic accuracy by 10 or 18%, respectively. Conclusion The addition of IHC either with CEA or MUC1 improved the diagnostic performance of the cytology alone to diagnose PAC. The cytology + IHC evaluation was superior to the cytology + KRAS mutation to diagnose PAC.