Evolving concepts in the cytology of pancreatic cystic and intraductal lesions.

Pancreatic cytopathology practice has changed significantly in the last few decades, most notably in the preoperative diagnosis of pancreatic cysts. Evolving concepts include reporting terminology and classification, ancillary testing, and management guidelines. Also, use of next-generation biopsy devices for sampling the cyst wall. The World Health Organization (WHO) reporting system for pancreaticobiliary cytopathology was recently published and updates the Papanicolaou Society of Cytopathology reporting system. The categories of neoplastic: benign and neoplastic: other are replaced by the categories of pancreaticobiliary neoplasm low or high risk/grade to better classify the risk of progression in mucinous cysts. The WHO system emphasizes the need for correlation with radiological, clinical, and ancillary studies, and provides a risk of malignancy and management recommendations for each category. Preoperative diagnosis and prediction of risk of disease progression of pancreatic cystic neoplasms has improved with biochemical analysis and molecular testing. A complex issue for clinicians treating patients with pancreatic cysts is whether to resect, continue surveillance, or dismiss patients from surveillance. Management guidelines for the management of pancreatic cysts are designed to guide clinicians in making these decisions. The role of cytology has been refined to specify identification of features predictive of at least high-grade dysplasia. Finally, the tissue yield by endoscopic ultrasound-guided sampling of pancreatic masses has improved with the addition of next-generation biopsy devices. The use of these advanced needles promises to improve the yield of cytological material. This article summarizes these evolving concepts in pancreatic cytology.