The aim of this study was to determine the diagnostic yield of the molecular analysis of K-RAS (Kirsten RAt Sarcoma virus) and GNAS (Guanine Nucleotide-binding protein, Alpha Stimulating protein activity) gene mutations in pancreatic cyst fluid (PCF) obtained by endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA). This evidence concerns the gene GNAS and Pancreatic cysts.