Fine needle aspiration of pancreatic cystic epithelial neoplasms.

Pancreatic cystic epithelial neoplasms present diagnostic challenges in cytology. An accurate diagnosis is important since the prognosis and treatment may vary. We report the cytologic features in fine needle aspirates of four cases of cystic neoplasms of the pancreas (two micro-cystic adenomas, one mucinous cystic neoplasm and one mucinous cystadenocarcinoma). Smears were evaluated as to their cellularity, content and predominant cell type. Aspirates from the microcystic adenomas yielded hypocellular material with rare strips of cuboidal cells having bland nuclei and pale cytoplasm. No mucinous material was identified in the background, but the cells stained positively with periodic acid-Schiff stain. Smears from the mucinous cystic neoplasm were moderately cellular and contained abundant mucinous material. The columnar epithelial cells were arranged in tight sheets, clusters and strips. Most cells had benign nuclear features with focal mild nuclear atypia. Key cytologic findings noted in the mucinous cystadenocarcinoma were moderate cellularity, loose clusters of cells, single cells, overt malignant nuclear features and occasional signet ring cells. Pancreatic pseudocysts can be distinguished from pancreatic cystic epithelial neoplasms by the predominance of histiocytes and inflammatory cells and absence or paucity of epithelial cells. To differentiate microcystic adenomas from mucinous cystic neoplasms, the above criteria coupled with periodic acid-Schiff and mucin staining should effectively differentiate these diagnostic entities.