The Role of Cytology

Abstract

Cytology forms an integral part of the multidisciplinary and multimodality approach required for the diagnosis of pancreatic lesions. Pancreatic fine needle aspiration cytology specimens may be obtained percutaneously under radiological guidance or via endoscopic ultrasound guidance. Sample preparation methods are discussed, since high-quality preparations are essential in facilitating diagnostic assessment. An approach to the diagnostic evaluation of pancreatic cytology cases is outlined, and features of contaminants from the sampling route are described. Pancreatic lesions may be usefully divided into cystic and solid entities. Interpretation of samples from cystic lesions includes consideration of biochemical analysis of cyst fluid. The cytological features of the most commonly encountered non-mucinous pancreatic cysts are described, followed by discussion of the challenging interpretation of mucinous cysts, including grading of cytological atypia. Solid lesions are separately discussed as inflammatory and neoplastic entities. The use of immunohistochemistry is outlined in the differential diagnosis of pancreatic endocrine neoplasms, acinar cell carcinoma, and solid-pseudopapillary neoplasm, and secondary involvement of the pancreas by malignancy is also discussed. This chapter also includes the interpretation of bile duct brushing cytology with description of the cytological features seen in benign, reactive, and malignant brushings.

This chapter is contributed by Durgesh N. Rana and Sakinah A. Thiryayi.