Molecular diagnostics of pancreatic cysts

ACR Appropriateness Criteria® Pancreatic Cyst

Incidental pancreatic cysts are increasingly detected on imaging studies performed for unrelated indications and may be incompletely characterized on these studies. Adequate morphological characterization is critical due to the small risk of malignant degeneration associated with neoplastic pancreatic cysts, as well as the risk of associated pancreatic adenocarcinoma. For all pancreatic cysts, both size and morphology determine management. Specifically, imaging detection of features, such as pancreatic ductal communication and presence or absence of worrisome features or high-risk stigmata, have important management implications. The recommendations in this publication determine the appropriate initial imaging study to further evaluate a pancreatic cyst that was incidentally detected on a nondedicated imaging study. The recommendations are designed to maximize the yield of diagnostic information in order to better risk-stratify pancreatic cysts and assist in guiding future management. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Pancreatic Cysts: Diagnostic Role of EUS-Guided Microforceps Biopsy and Confocal Laser Endomicroscopy

Frequent use of high-quality cross-sectional imaging has led to a significant rise in diagnosis of pancreatic cystic lesions (PCLs). Despite the fact that enormous effort has been put into the research of PCLs within the last two decades and multiple guidelines have been developed, our clinical decision-making especially in regard to mucinous lesions remains limited. Currently, clinical assessment, cross-sectional imaging and EUS with fluid analysis (if appropriate) belong to the standard care in patients with PCLs. For differentiation of mucinous from nonmucinous cysts, the sensitivity of cytological investigation and CEA in the cyst fluid is 42% and 52-79%, respectively. Due to the limited accuracy, further diagnostic tools are warranted. Two EUS-guided approaches have been introduced recently. Through-the-(19-gauge EUS) needle Moray microforceps have been developed, and several studies have acknowledged their contribution to the correct diagnosis as they help to overcome limited cellularity of the EUS-guided cyst fluid aspiration and traditional cytology. Confocal laser endomicroscopy offers real-time images and seems to be a promising method for the diagnosis and differential diagnosis of pancreatic PCLs. Example images of the needle-based confocal laser endomicroscopy criteria for the diagnosis of PCLs have been suggested recently. Before both, Moray microforceps and confocal laser endomicroscopy can be widely accepted, further studies are necessary to determine the real diagnostic yield and the clinical efficacy.

DNA testing of pancreatic cyst fluid: is it ready for prime time?

Pancreatic cysts are a clinical quandary in both diagnosis and management. Although many cysts, such as pseudocysts and serous cystadenomas, are benign and can be monitored clinically, mucinous cysts, such as intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, have the potential to progress to pancreatic cancer. Considering the poor prognosis of pancreatic cancer, the detection of a pancreatic cyst can be a source of anxiety for both the patient and physician. This diagnosis in turn can lead to expensive, invasive, and even harmful surveillance and treatment options. As a consequence, several national and international guidelines for the management of pancreatic cysts have been developed over the past decade. However, these guidelines rely on standard clinical assessment, radiographical imaging, and ancillary fluid studies that have insufficient sensitivity and specificity. The application of DNA-based molecular techniques has emerged as an adjunct to the assessment of pancreatic cysts. The cellular content of pancreatic cyst fluid aspirate is often suboptimal for analysis, but DNA isolated from lysed or exfoliated cells within the cyst can be analysed for genetic abnormalities. Moreover, whole exome sequencing and targeted sequencing of the major pancreatic cysts has identified unique mutational profiles for cyst type and genetic alterations that coincide with the development of pancreatic cancer. In this Review, we discuss the major cystic lesions of the pancreas and their underlying molecular pathology, current management guidelines for pancreatic cysts, and integration of DNA-based molecular testing within this field.

Molecular Characterization and Pathogenesis of Intraductal Papillary Mucinous Neoplasms of the Pancreas

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are noninvasive neoplasms which occur in the main pancreatic duct or its major branches. IPMNs have an important meaning in the clinic and in research since they represent around 20% of all resected pancreatic neoplasms. Morphologically, branch duct, main duct and mixed-type IPMNs can be distinguished. Histologically, they can be divided into gastric, intestinal, pancreatobiliary and oncocytic type. There are different mutations in genes such as KRAS, GNAS, RNF43 and p53. The expression of miRNAs is specific to IPMNs; altogether, 14 miRNAs have been identified so far which are differently expressed in all IPMNs in contrast to normal pancreatic tissue. It has also been observed that methylation levels can be altered in IPMNs. This review summarizes the molecular characteristics of IPMNs of the pancreas and presents currently known markers.