title: Inter-Observer Variation in the Pathologic Identification of Extranodal Extension in Nodal Metastasis from Papillary Thyroid Carcinoma.
abstract: Extranodal extension (ENE) in lymph node metastases has been shown to worsen the prognosis of papillary thyroid cancer (PTC). Despite the clinical significance of ENE, there are no stringent criteria for its microscopic diagnosis, and its identification is subject to inter-observer variability. The objective of this study was to determine the level of agreement among expert pathologists in the identification of ENE in PTC cases.
  
  
  
  Eleven expert pathologists from the United States, Italy, and Canada were asked to review 61 scanned slides of representative permanent sections of PTC specimens from Mount Sinai Beth Israel Medical Center in New York. Each slide was evaluated for the presence of ENE. The pathologists were also asked to report the criteria they use to identify ENE.
  
  
  
  The overall strength of agreement in identifying ENE was only fair (κ = 0.35), and the proportion of observed agreement was 0.68. The proportions of observed agreement for the identification of perinodal structures (fat, nerve, skeletal, and thick-walled vessel involvement) ranged from 0.61 to 0.997.
  
  
  
  Overall agreement for the identification of ENE is poor. The lack of agreement results from both variation in pathologists' identification of features and disagreement on the histologic criteria for ENE. This lack of concordance may help explain some of the discordant information regarding prognosis in clinical studies when this feature is identified.
authors.affiliation: 1 Department of Otorhinolaryngology-Head and Neck Surgery, Montefiore Medical Center, Albert Einstein College of Medicine , Bronx, New York.
authors.forename: Eugenie
authors.initials: E
authors.lastname: Du
authors.affiliation: 2 Department of Pathology, Mount Sinai Beth Israel , New York, New York.
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Wenig
authors.affiliation: 3 Thyroid, Head and Neck Cancer (THANC) Foundation , New York, New York.
authors.forename: Henry K
authors.initials: HK
authors.lastname: Su
authors.affiliation: 3 Thyroid, Head and Neck Cancer (THANC) Foundation , New York, New York.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Rowe
authors.affiliation: 3 Thyroid, Head and Neck Cancer (THANC) Foundation , New York, New York.
authors.forename: Grace C
authors.initials: GC
authors.lastname: Haser
authors.affiliation: 4 Department of Pathology, Laboratory Medicine Program, Toronto General Hospital , Toronto, Canada .
authors.forename: Sylvia L
authors.initials: SL
authors.lastname: Asa
authors.affiliation: 5 Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania , Philadelphia, Pennsylvania.
authors.forename: Zubair
authors.initials: Z
authors.lastname: Baloch
authors.affiliation: 6 Department of Pathology, Massachusetts General Hospital , Boston, Massachusetts.
authors.forename: William C
authors.initials: WC
authors.lastname: Faquin
authors.affiliation: 7 Centro Consulenze Anatomia Patologica Oncologica, Centro Diagnostico Italiano , Milan, Italy .
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fellegara
authors.affiliation: 8 Department of Pathology, University of Michigan Medical School , Ann Arbor, Michigan.
authors.forename: Thomas
authors.initials: T
authors.lastname: Giordano
authors.affiliation: 9 Department of Pathology, Memorial Sloan-Kettering Cancer Center , New York, New York.
authors.forename: Ronald
authors.initials: R
authors.lastname: Ghossein
authors.affiliation: 5 Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania , Philadelphia, Pennsylvania.
authors.forename: Virginia A
authors.initials: VA
authors.lastname: LiVolsi
authors.affiliation: 10 Department of Pathology and Laboratory Medicine, University of Wisconsin , Madison, Wisconsin.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Lloyd
authors.affiliation: 4 Department of Pathology, Laboratory Medicine Program, Toronto General Hospital , Toronto, Canada .
authors.forename: Ozgur
authors.initials: O
authors.lastname: Mete
authors.affiliation: 11 Population Health Science and Policy, Mount Sinai Hospital , New York, New York.
authors.forename: Umut
authors.initials: U
authors.lastname: Ozbek
authors.affiliation: 7 Centro Consulenze Anatomia Patologica Oncologica, Centro Diagnostico Italiano , Milan, Italy .
authors.forename: Juan
authors.initials: J
authors.lastname: Rosai
authors.affiliation: 12 Department of Pathology, Medical College of Wisconsin , Milwaukee, Wisconsin.
authors.forename: Saul
authors.initials: S
authors.lastname: Suster
authors.affiliation: 13 Department of Pathology, Woodland Hills Medical Center , Woodland Hills, California.
authors.forename: Lester D
authors.initials: LD
authors.lastname: Thompson
authors.affiliation: 14 Department of Pathology, New York-Presbyterian/Columbia , New York, New York.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Turk
authors.affiliation: 15 Department of Otolaryngology-Head and Neck Surgery, Mount Sinai Beth Israel , New York, New York.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Urken
mesh_terms: D002291:Carcinoma, Papillary / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology*; D015588:Observer Variation; D011379:Prognosis; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology*