Cystic Lesions of the Pancreas: Differential Diagnosis and Cytologic-Histologic Correlation

Pancreatic cystic lesions (PCLs) comprise a broad spectrum of entities and can be categorized into neoplastic and nonneoplastic. They differ greatly in their clinical behavior and malignant potential. Neoplastic cystic [...]
* Context.--Pancreatic cystic lesions (PCLs) are very common, and their detection is increasing with the advances in imaging techniques. Because of the major implications for management, distinguishing between neoplastic and nonneoplastic PCLs is critical. Neoplastic cysts with potential to progress into cancer include mucinous PCLs (intraductal papillary mucinous neoplasms and mucinous cystic neoplasms) and nonmucinous cysts (solid pseudopapillary tumors, serous cystic neoplasms, and neuroendocrine tumors with cystic degeneration). Nonneoplastic cysts with no risk of malignant transformation include pseudocysts, retention cysts, lymphoepithelial cysts, cystic pancreatic lymphangioma, and duplication cyst/ciliated foregut cysts. The role of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology with cyst fluid analysis in the diagnosis of PCLs has evolved during the last decade; however, a definitive diagnosis on cytologic specimens is hampered by the sparse cellularity and can be challenging. EUS-FNA can play an important role to differentiate low-risk from high-risk pancreatic cysts and to distinguish between patients with cysts who need clinical follow-up versus those who require surgery. Objective.--To provide an integrative approach to diagnose pancreatic cystic lesions using EUS-FNA cytology and cyst fluid analysis, along with clinical, radiologic, histologic, genetic, and molecular characteristics. Data Sources.--The review and analysis of the latest literature describing pancreatic cystic lesions. Conclusions.--Accurate diagnosis of PCLs requires a multidisciplinary and multimodal team approach, including the integration of clinical findings, imaging, cytology, cyst fluid analysis, and molecular testing. (Arch Pathol Lab Med. 2020;144:47-61; doi: 10.5858/arpa.2019-0308-RA)