Role of endoscopic ultrasonography in pancreatic cystic neoplasms: where do we stand and where will we go?

We increasingly encounter pancreatic cystic neoplasms (PCN) in clinical practice and the differential diagnoses vary widely from benign to malignant. There is no 'one and only' diagnostic procedure for PCN. Multiple modalities including computed tomography, magnetic resonance imaging, endoscopic retrograde cholangiopancreatography and endoscopic ultrasound (EUS) are widely used, but EUS has the advantage of anatomical proximity to the pancreas and upper gastrointestinal tract. In addition, EUS-guided fine-needle aspiration (EUS-FNA) provides both cytological evaluation and cyst fluid analysis. Although the role of EUS-FNA for PCN is established, the sensitivity of cytology is low and cyst fluid analysis is only useful for differentiation between mucinous and non-mucinous cysts. Recently, novel through-the-needle imaging under EUS-FNA, such as confocal laserendomicroscopy, is expected to attribute to a better diagnostic yield. Moreover, feasibility of cyst ablation has been reported and the role of EUS has expanded from diagnosis to treatment. However, clinical impact of cyst ablation in terms of safety, efficacy and cost-effectiveness should be validated further. In summary, EUS and EUS-guided intervention does and will play a central role in the management of PCN from surveillance to treatment, but many clinical questions remain unanswered, which warrants well-designed prospective clinical trials.