title: Cytologic separation of branchial cleft cyst from metastatic cystic squamous cell carcinoma: A multivariate analysis of nineteen cytomorphologic features.
abstract: BACKGROUND
  The separation of branchial cleft cysts from metastatic cystic squamous cell carcinomas in adults can be clinically and cytologically challenging. Diagnostic accuracy for separation is reported to be as low as 75% prompting some authors to recommend frozen section evaluation of suspected branchial cleft cysts before resection. We evaluated 19 cytologic features to determine which were useful in this distinction.
  
  
  METHODS
  Thirty-three cases (21 squamous carcinoma and 12 branchial cysts) of histologically confirmed cystic lesions of the lateral neck were graded for the presence or absence of 19 cytologic features by two cytopathologists. The cytologic features were analyzed for agreement between observers and underwent multivariate analysis for correlation with the diagnosis of carcinoma.
  
  
  RESULTS
  Interobserver agreement was greatest for increased nuclear/cytoplasmic (N/C) ratio, pyknotic nuclei, and irregular nuclear membranes. Recursive partitioning analysis showed increased N/C ratio, small clusters of cells, and irregular nuclear membranes were the best discriminators.
  
  
  CONCLUSIONS
  The distinction of branchial cleft cysts from cystic squamous cell carcinoma is cytologically difficult. Both digital image analysis and p16 testing have been suggested as aids in this separation, but analysis of cytologic features remains the main method for diagnosis. In an analysis of 19 cytologic features, we found that high nuclear cytoplasmic ratio, irregular nuclear membranes, and small cell clusters were most helpful in their distinction. Diagn. Cytopathol. 2016;44:561-567. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri.
authors.forename: Lester J
authors.initials: LJ
authors.lastname: Layfield
authors.affiliation: Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri.
authors.forename: Magda
authors.initials: M
authors.lastname: Esebua
authors.affiliation: Department of Pathology and Laboratory Medicine and ARUP Laboratories, University of Utah, Salt Lake City, Utah.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D044963:Biopsy, Fine-Needle; D001935:Branchioma / Q000145:classification / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000556:secondary; D015925:Cryopreservation; D003937:Diagnosis, Differential; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000556:secondary; D006801:Humans; D012680:Sensitivity and Specificity
keywords: branchial cyst; cystic squamous carcinoma; cytologic features; fine-needle aspiration