Abstract
Objective : We discuss the cytological, histological, and immunostaining features of solid pseudopapillary tumors (SPT) without pancreatic cyst formation as they compare to endocrine tumors (ET).
Study Design : Cytological, histological, and immunohistochemical examinations were conducted on surgically resected SPT and ET.
Results : SPTs without cyst formation consisted of small uniformly sized and shaped epithelial cells having solid and pseudopapillary patterns with hypovascular arborizing stroma. Imprint cytology showed 1) numerous small epithelial cells distributed singly and in loose fragments with ill-defined cytoplasm, monomorphic nuclei, and finely granular, even chromatin, and 2) peculiarly shaped fibrillary myxoid stroma substances. Immunohistochemistry showed an SPT phenotype strongly expressing vimentin and α1-antichymotrypsin, but lacking CK/CAM5.2 and chromogranin A expression, unlike the ET phenotype. SPTs also demonstrated intranuclear β-catenin and cyclin D1 accumulation.
Conclusion : Cytological and immunostaining features of pancreatic SPT, being highly specific, are extremely useful in supporting SPT and excluding ET diagnosis.
