Cytologic features of solid pseudopapillary neoplasms of the pancreas: a single institutional experience based on evaluation of diagnostic utility of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA)

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an important modality for diagnosing solid and cystic pancreatic lesions. The objectives of this retrospective study are to review the cytologic criteria used to diagnose pancreatic solid pseudopapillary neoplasms (SPNs) and to evaluate the utility of EUS-FNA by correlating cytologic and histologic samples. Of the 924 pancreatic FNAs performed at our institution from January 2002 through February 2013, four histologically confirmed cases of SPN were identified; three had an initial cytologic diagnosis of SPN. All four cases lacked on-site evaluation. Cytologic smears were assessed by two reviewers for the presence of a cellular aspirate, fibrovascular stalks lined by neoplastic cells with pale to finely granular cytoplasm, and monotonous, oval nuclei containing delicate chromatin, inconspicuous nucleoli, and grooves and inclusions. Three cases were diagnosed as SPN on cytologic examination and confirmed histologically. The remaining case was deemed a pancreatic endocrine neoplasm on cytology, but SPN on final histology. The most consistent cytologic feature we encountered was the presence of a cellular aspirate containing fibrovascular stalks lined by monotonous neoplastic cells with oval nuclei and nuclear grooves. We conclude that EUS-FNA is an effective diagnostic tool in the diagnosis of pancreatic SPNs.