title: Cytomorphologic and immunophenotypical features of acinar cell neoplasms of the pancreas.
abstract: BACKGROUND
  Acinar cell neoplasms of the pancreas are rare but when encountered, the diagnosis is often established based on cytology specimens. Diagnostic accuracy is important because acinar cell carcinomas are aggressive yet may mimic tumors with different outcomes and management.
  
  
  METHODS
  The authors identified all patients with a diagnosis of acinar cell neoplasm in the institutional database; assessed cytomorphology and immunocytochemistry for trypsin, chymotrypsin, synaptophysin, chromogranin A, and MIB-1; and compared all cytology and final histological diagnoses for diagnostic discrepancies.
  
  
  RESULTS
  Cytological features were described for 16 histologically proven malignant acinar cell neoplasms: acinar cell carcinoma (8 cases), mixed acinar-neuroendocrine carcinoma (6 cases), mixed acinar-ductal carcinoma (1 case), and pancreatoblastoma (1 case).The majority of aspirates from acinar cell cystadenomas were nondiagnostic or negative (5 of 6 cases; 83%). Acinar and neuroendocrine differentiation that was detected by immunocytochemistry in >20% of tumor cells was found to be correlated with mixed acinar-neuroendocrine carcinoma histology. Cytohistological correlation included 32 patients with 17 discordant diagnoses (53%). The following preoperative cytology diagnoses proved to be acinar cell neoplasms on resection: neuroendocrine tumor (5 cases), adenocarcinoma (5 cases), atypical ductal cells (2 cases), solid pseudopapillary neoplasm, and hepatocellular carcinoma. Three aspirates diagnosed as acinar cell carcinoma by cytology proved to be chronic pancreatitis (2 cases) and ductal adenocarcinoma (1 case).
  
  
  CONCLUSIONS
  Acinar cell carcinoma has a distinctive cytological appearance but is frequently misdiagnosed on cytology. Immunocytochemistry is useful for identifying acinar differentiation.
authors: Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New YorK, USA. sigelc@mskcc.org
authors: Carlie S
authors: CS
authors: Sigel
authors: David S
authors: DS
authors: Klimstra
mesh_terms: D000328:Adult; D018267:Carcinoma, Acinar Cell / Q000378:metabolism / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology*
keywords: acinar cell carcinoma; fine-needle biopsy; immunohistochemistry; neuroendocrine tumors; pancreatic acinar carcinoma; pancreatoblastoma