title: Performance of endoscopic ultrasound-guided fine needle aspiration in diagnosing pancreatic neuroendocrine tumors.
abstract: BACKGROUND
  Pancreatic neuroendocrine tumors (PNETs) are rare tumors of the pancreas, which are increasingly diagnosed by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). In this retrospective study, we assessed the performance of EUS-FNA in diagnosing PNETs.
  
  
  METHODS
  We identified 48 cases of surgically resected PNETs in which pre-operative EUS-FNA was performed. The clinical features, cytological diagnoses, and surgical follow-up were retrospectively reviewed. The diagnostic performance of EUS-FNA was analyzed as compared to the diagnosis in the follow-up. The cases with discrepancies between cytological diagnosis and surgical follow-up were analyzed and diagnostic pitfalls in discrepant cases were discussed.
  
  
  RESULTS
  The patients were 20 male and 28 female with ages ranging from 15 years to 81 years (mean 57 years). The tumors were solid and cystic in 41 and 7 cases, respectively, with sizes ranging from 0.5 cm to 11 cm (mean 2.7 cm). Based on cytomorphologic features and adjunct immunocytochemistry results, when performed, 38 patients (79%) were diagnosed with PNET, while a diagnosis of suspicious for PNET or a diagnosis of neoplasm with differential diagnosis including PNET was rendered in the 3 patients (6%). One case was diagnosed as mucinous cystic neoplasm (2%). The remaining 6 patients (13%) had non-diagnostic, negative or atypical diagnosis.
  
  
  CONCLUSIONS
  Our data demonstrated that EUS-FNA has a relatively high sensitivity for diagnosing PNETs. Lack of additional materials for immunocytochemical studies could lead to a less definite diagnosis. Non-diagnostic or false negative FNA diagnosis can be seen in a limited number of cases, especially in those small sized tumors.
authors.affiliation: Department of Pathology and Internal Medicine, Yale University, School of Medicine, New Haven, Connecticut, USA.
authors.forename: Jane
authors.initials: J
authors.lastname: Bernstein
authors.forename: Berrin
authors.initials: B
authors.lastname: Ustun
authors.forename: Ahmed
authors.initials: A
authors.lastname: Alomari
authors.forename: Fang
authors.initials: F
authors.lastname: Bao
authors.forename: Harry R
authors.initials: HR
authors.lastname: Aslanian
authors.forename: Uzma
authors.initials: U
authors.lastname: Siddiqui
authors.forename: David
authors.initials: D
authors.lastname: Chhieng
authors.forename: Guoping
authors.initials: G
authors.lastname: Cai
keywords: Cytomorphology; fine needle aspiration; immunocytochemistry; neuroendocrine tumor; pancreas