title: Hints to the diagnosis of mixed acinar-endocrine carcinoma on pancreatic fine-needle aspiration: avoiding a potential diagnostic pitfall.
abstract: BACKGROUND
  Mixed acinar-endocrine carcinoma (MAEC) is a rare mixed tumor of the pancreas defined by both acinar and endocrine cell differentiation.
  
  
  METHODS
  We present 2 cases of MAEC initially diagnosed as pancreatic endocrine neoplasm on fine-needle aspiration. Both patients were male, aged 51 and 75 years, and presented with 16-mm and 6-mm pancreatic masses, respectively. Aspirates showed loose aggregates and dispersed single plasmacytoid cells with moderate nuclear size variation, slightly irregular nuclear contours, fine to coarsely granular chromatin, occasional prominent nucleoli, and scant to moderate finely granular cytoplasm. Rare mitotic figures and pyknotic forms were noted in one of the cases. Endocrine differentiation was confirmed by immunocytochemistry which led to an initial diagnosis of pancreatic endocrine neoplasm. Trypsin and lipase immunocytochemistry were later obtained, confirming a component of acinar cell differentiation. Findings were confirmed on surgical excision.
  
  
  CONCLUSIONS
  Because of their potentially more aggressive clinical course and different therapeutic implications, MAECs are an important consideration in the differential diagnosis of pancreatic neoplasms. Certain cytomorphologic features and immunocytochemical markers of acinar cell differentiation may be helpful in raising the possibility of MAEC on cytology.
authors: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, Calif. 90095-1732, USA. psullivan@mednet.ucla.edu
authors: Peggy S
authors: PS
authors: Sullivan
authors: Jennifer L
authors: JL
authors: Clebanoff
authors: Sharon L
authors: SL
authors: Hirschowitz
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D002454:Cell Differentiation; D003951:Diagnostic Errors / Q000517:prevention & control*; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018193:Neoplasms, Complex and Mixed / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D046790:Pancreas, Exocrine / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D010180:Pancreatectomy; D010190:Pancreatic Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D011237:Predictive Value of Tests
chemical_list: D014408:Biomarkers, Tumor