Differentiating neoplastic from benign lesions of the pancreas: translational techniques

There has been substantial recent progress in our ability to image and sample the pancreas leading to the improved recognition of benign and premalignant conditions of the pancreas such as autoimmune pancreatitis (AIP) and mucinous lesions (mucinous cystic neoplasms [MCN] and intraductal papillary mucinous neoplasms [IPMN]), respectively. Clinically relevant and difficult situations that continue to be faced in this context include differentiating MCN and IPMN from nonmucinous pancreatic cysts, the early detection of malignant degeneration in MCN and IPMN, and accurate differentiation between pancreatic cancer and inflammatory masses, especially AIP. These challenges arise primarily due to the less than perfect sensitivity for malignancy utilizing cytological samples obtained via EUS and ERCP. Aspirates from pancreatic cysts are often paucicellular further limiting the accuracy of cytology. One approach to improve the diagnostic yield from these very small samples is through the use of molecular techniques. Because the development of pancreatic cancer and malignant degeneration in MCN and IPMN is associated with well studied genetic insults including oncogene activation (eg, k-ras), tumor suppressor gene losses (eg, p53, p16, and DPC4), and genome maintenance gene mutations (eg, BRCA2 and telomerase), detecting these molecular abnormalities may aid in improving our diagnostic accuracy. A number of studies have shown the utility of testing clinical samples from pancreatic lesions and bile duct strictures for these molecular markers of malignancy to differentiate between cancer and inflammation. The information from these studies will be discussed with emphasis on how to use this information in clinical practice.