Cytopathology of Pancreatic Cystic Lesions

Pancreatic cystic lesions include both neoplastic and non-neoplastic entities with varying malignant potential and constitute significant diagnostic and management challenges. The increased use of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has improved the detection and characterization of these lesions. Cytologic evaluation differentiates non-neoplastic from neoplastic cysts, and also identifies mucinous from nonmucinous lesions, and dysplasia or malignancy in mucinous neoplasms. Specific diagnosis requires a unified multidisciplinary approach that combines cytomorphologic features with clinical findings, imaging characteristics, cyst fluid biochemistry, and molecular analysis. Recent advances, including standardized WHO reporting systems, immunocytochemistry, and molecular profiling, have enhanced diagnostic accuracy and risk stratification. This chapter provides a comprehensive overview of the role of cytology in pancreatic cystic lesions, detailing sampling techniques, cytomorphologic features, diagnostic pitfalls, ancillary studies, and reporting frameworks, with an emphasis on a multimodal approach to guide optimal patient management.