title: Observer variation in the histopathologic assessment of extranodal tumor spread in lymph node metastases in the neck.
abstract: BACKGROUND
  Extranodal spread (ENS) of tumors is widely used as a prognosticator for patients with head and neck cancer and is used as an indicator for postoperative treatment. However, the histopathologic agreement among pathologists on the assessment of the presence or absence of this criterion has never been studied.
  
  
  METHODS
  The interobserver and intraobserver agreement among 10 pathologists on the diagnosis of ENS in 41 tumor-positive lymph nodes was evaluated.
  
  
  RESULTS
  The kappa value of the interobserver agreement among pathologists varied between 0.14 and 0.75, the overall kappa value was 0.42 and 0.49 in the 2 scoring sessions. The intraobserver kappa value varied between 0.49 and 0.95.
  
  
  CONCLUSIONS
  The intraobserver and interobserver agreement among pathologists in the assessment of the presence of ENS was low in metastatic lymph nodes in the neck. Because of the widely accepted prognostic significance and therapeutic consequences of ENS, there is a need for internationally accepted reproducible criterion for the histopathologic assessment of ENS in metastatic lymph nodes in the neck.
authors.affiliation: Department of Head and Neck Surgery and Oncology, Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands. m.vd.brekel@nki.nl
authors.forename: Michiel W M
authors.initials: MW
authors.lastname: van den Brekel
authors.forename: Wouter L
authors.initials: WL
authors.lastname: Lodder
authors.forename: Herbert V
authors.initials: HV
authors.lastname: Stel
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bloemena
authors.forename: C René
authors.initials: CR
authors.lastname: Leemans
authors.forename: Isaäc
authors.initials: I
authors.lastname: van der Waal
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology*; D037981:Neck Dissection; D015588:Observer Variation; D012189:Retrospective Studies