title: The differential diagnosis of squamous cells in pancreatic aspirates: from contamination to adenosquamous carcinoma.
abstract: BACKGROUND
  This study was conducted to describe the frequency and significance of squamous cells in fine needle aspiration (FNA) specimens of the pancreas in benign and malignant processes.
  
  
  METHODS
  A retrospective review was performed of 102 patients with squamous cells in their pancreatic FNA specimens from 1986 to 2012. The malignant cases were classified as adenosquamous carcinoma (ASqC) or metastatic squamous cell carcinoma, and a double institutional review of the ASqC cases was undertaken to characterize the clinical and pathological features and survival statistics of patients who present with unresectable or metastatic ASqC and have no follow-up surgery. Survival analyses were performed.
  
  
  RESULTS
  Of the 4,094 pancreas FNA procedures performed in the study, squamous features were found in 102 (2.5%) of all cases, and 48% of these cases represented ASqC. The other cases were contamination (52%) or atypical (<1%). ASqC constituted 4.5% (46/1,025) of all primary pancreatic exocrine malignancies. When compared with conventional adenocarcinoma, ASqC demonstrated a significantly poorer overall median survival (11.0 vs. 6.51 months; p = 0.023), and this difference was also seen in patients presenting with metastatic disease (median survival of 9.1 vs. 4.2 months; p = 0.025).
  
  
  CONCLUSIONS
  Squamous cells in FNA specimens from the pancreas have a broad differential diagnosis that ranges from contamination to ASqC.
authors: Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA.
authors: Matthew T
authors: MT
authors: Olson
authors: Momin T
authors: MT
authors: Siddiqui
authors: Syed Z
authors: SZ
authors: Ali
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015142:Baltimore; D044963:Biopsy, Fine-Needle; D018196:Carcinoma, Adenosquamous / Q000401:mortality / Q000473:pathology* / Q000556:secondary; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology* / Q000556:secondary; D003937:Diagnosis, Differential; D005260:Female; D005845:Georgia; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies