title: Utility of Flow Cytometry in Diagnosing Hematologic Malignancy in Tonsillar Tissue.
abstract: OBJECTIVE
  Tonsil surgical biopsy or excision is a very common procedure. However, there exist no consensus guidelines for the pathologic handling of tonsil specimens; gross and/or microscopic evaluation may be used. Diagnosis of tonsillar hematologic malignancy requires histology, immunohistochemistry and/or flow cytometry. Data regarding the utility of flow cytometry in tonsillar tissues are limited. We assessed our experience with flow cytometry for tonsil diagnosis with regard to accuracy and use patterns at a tertiary academic medical center.
  
  
  METHODS
  We retrospectively analyzed all surgically biopsied or excised tonsil specimens that underwent flow cytometry evaluation from August 2011 to March 2014. Patient clinical information, intraoperative frozen section, histology, immunohistochemistry, and flow cytometry diagnoses were recorded.
  
  
  RESULTS
  The study included 154 tonsil specimens from 89 females and 65 males. Patients averaged 27.4 years old (range 2-87 years); 73 were pediatric. Both histology and flow cytometry were benign for 148 patients (96.1%). Hematolymphoid malignancy was diagnosed in 6 adults by histology/immunohistochemistry: diffuse large B-cell lymphoma (2), small B-cell lymphoma (2), concomitant follicular lymphoma and histiocytic sarcoma (1), and extraosseous plasmacytoma (1). Flow cytometry identified abnormal populations in 5 of 6 cases, and detected clonal populations in 2 reactive follicular hyperplasia cases.
  
  
  CONCLUSIONS
  Tonsillar hematolymphoid malignancy is uncommon, and flow cytometry was less accurate than histology/immunohistochemistry for its diagnosis. Despite the rarity of tonsillar lymphoma in children, nearly half of study patients were pediatric. Intraoperative frozen section diagnosis showed excellent sensitivity for malignancy, and could be used to effectively triage cases for flow cytometry evaluation.
authors.affiliation: 1 Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Omonigho
authors.initials: O
authors.lastname: Aisagbonhi
authors.affiliation: 1 Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: DeLelys
authors.affiliation: 1 Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Hartford
authors.affiliation: 1 Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Frederic
authors.initials: F
authors.lastname: Preffer
authors.affiliation: 1 Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Ly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry / Q000191:economics / Q000706:statistics & numerical data*; D005629:Frozen Sections; D019337:Hematologic Neoplasms / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D014066:Palatine Tonsil / Q000473:pathology* / Q000601:surgery; D035583:Rare Diseases / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D014067:Tonsillar Neoplasms / Q000473:pathology* / Q000601:surgery; D014068:Tonsillectomy; D055815:Young Adult
keywords: accuracy; flow cytometry; immunohistochemistry; lymphoma; tonsil