title: Intraductal Tubulopapillary Neoplasm of the Pancreas Masquerading as Pancreatic Neuroendocrine Carcinoma: Review of the Literature with a Case Report.
abstract: BACKGROUND
  Intraductal tubulopapillary neoplasm of the pancreas (ITPN) is a rare tumor which was first described in 2009. We report a case with cytologic and histologic findings and discuss the pitfalls in diagnosing this entity on cytology.
  
  
  METHODS
  An 82-year-old female presented with a pancreatic body mass measuring 3.3 cm. Endoscopic ultrasound-guided fine-needle aspiration showed cells in cohesive clusters with high-grade nuclear atypia. Immunohistochemistry (IHC) showed the neoplastic cells to be positive for CK19, CD56 and chromogranin (focal). Ki-67 was high at 50-60%, and chymotrypsin was negative. On the basis of this pattern of staining, the cytologic diagnosis rendered was 'favors high-grade neuroendocrine carcinoma'. Distal pancreatic resection revealed a cystic 4-cm mass. Histologically, the tumor was seen arising from the duct with a solid growth pattern, tubule formation and papillary structures. IHC showed the tumor to be negative for chromogranin, synaptophysin, CD56, trypsin and chymotrypsin. The Ki-67 index was 70%. The final diagnosis was noninvasive ITPN.
  
  
  CONCLUSIONS
  We review the literature and discuss the cytomorphologic features and IHC patterns characteristic of this new entity on cytology material in addition to the pitfalls of the cytologic diagnosis.
authors.affiliation: Department of Pathology and Laboratory Medicine, Hofstra Northwell School of Medicine, New Hyde Park, N.Y., USA.
authors.forename: Deepika
authors.initials: D
authors.lastname: Savant
authors.forename: Lili
authors.initials: L
authors.lastname: Lee
authors.forename: Kasturi
authors.initials: K
authors.lastname: Das
mesh_terms: D000369:Aged, 80 and over; D018278:Carcinoma, Neuroendocrine / Q000473:pathology*; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration / Q000379:methods; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D010179:Pancreas / Q000473:pathology*; D010180:Pancreatectomy / Q000379:methods; D010190:Pancreatic Neoplasms / Q000473:pathology*