title: The dilemma of "indeterminate" interpretations of pancreatic neuroendocrine tumors on fine needle aspiration.
abstract: BACKGROUND
  Indeterminate (atypical/suspicious) fine needle aspiration (FNA) interpretation of Pancreatic Neuroendocrine Tumor (PanNET) can be frustrating for both pathologists and clinicians. Although published literature has often addressed the significance of indeterminate cytologic diagnoses in non-neuroendocrine epithelial lesions, the significance of indeterminate FNA results for PanNET is less established.
  
  
  METHODS
  The pathology records of The Johns Hopkins hospital were searched for histologic diagnoses of PanNET that had corresponding pre-operative FNA results. Cytopathologic diagnoses were categorized according to the index of suspicion described in the report (atypical, suspicious for PanNET and PanNET). Additionally, the exact reasons for the indeterminate nature of the diagnoses-such as lack of adequate cytologic features, unusual findings, or lack of confirmatory immunocytochemistry (ICC) were investigated.
  
  
  RESULTS
  One hundred and twenty (120) cases of PanNET were identified. Of these, the FNA diagnoses were as follows: 78% (94/120) were PanNET, 9% (11/120) were suspicious for PanNET, 6% (7/120) were atypical, 4% (5/120) were benign, 2% (2/120) were non-diagnostic and 1% (1/120) was called a mucinous neoplasm. Of the 94 cases that were definitively PanNET, 74 (78%) required ICC for the diagnosis. Of the 26 cases that were not diagnosed definitively as PanNET, 73% (19/26) were morphologically suggestive of PanNET but did not have sufficient material for confirmatory ICC.
  
  
  CONCLUSIONS
  ICC is commonly employed to confirm the cytologic suspicion for PanNET. The most common reasons for indeterminate diagnoses were a quantitative lack of lesional cells and lack of material for confirmatory ICC.
authors.affiliation: Department of Pathology, the Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Aadil
authors.initials: A
authors.lastname: Ahmed
authors.affiliation: Department of Pathology, the Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: VandenBussche
authors.affiliation: Department of Pathology, the Johns Hopkins University School of Medicine, Baltimore, Maryland.|Department of Radiology, the Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Syed Z
authors.initials: SZ
authors.lastname: Ali
authors.affiliation: Department of Pathology, the Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Olson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D044963:Biopsy, Fine-Needle; D019002:CD56 Antigen / Q000235:genetics*; D053379:Chromogranin A / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D012189:Retrospective Studies; D016708:Synaptophysin / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D019002:CD56 Antigen; C506150:CHGA protein, human; D053379:Chromogranin A; C522918:NCAM1 protein, human; C569014:SYP protein, human; D016708:Synaptophysin
keywords: FNA; PanNET; atypical; indeterminate; pancreatic neuroendocrine; suspicious