title: Evaluation of a new grading system for laryngeal squamous intraepithelial lesions--a proposed unified classification.
abstract: OBJECTIVE
  To verify the applicability, reproducibility and predictive value of a proposed unified classification (amended Ljubljana classification) for laryngeal squamous intraepithelial lesions (SILs).
  
  
  RESULTS
  Six internationally recognized experts and three pathologists from Ljubljana contributed to this study by evaluating a set of laryngeal SILs using the new system: low-grade SIL, high-grade SIL, and carcinoma in situ (CIS). The overall agreement among reviewers was good. Overall unweighted and weighted κ-values and 95% confidence intervals were 0.75 (0.65-0.84) and 0.80 (0.71-0.87), respectively. The results were stratified between the international reviewers and the Ljubljana pathologists. The former had good overall agreement, and the latter had very good agreement. Kaplan-Meier survival curves showed a significant difference (P < 0.0001) between patients with low-grade and high-grade SILs; 19 of 1204 patients with low-grade SILs and 30 of 240 patients with high-grade SILs progressed to malignancy in 2-15 years and in 2-26 years, respectively.
  
  
  CONCLUSIONS
  The proposed modification to the Ljubljana classification provides clear morphological criteria for defining the prognostic groups. The criteria facilitate better interobserver agreement than previous systems, and the retrospective follow-up study demonstrates a highly significant difference in the risk of malignant progression between low-grade and high-grade SILs.
authors.affiliation: Institute of Pathology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Nina
authors.initials: N
authors.lastname: Gale
authors.forename: Rok
authors.initials: R
authors.lastname: Blagus
authors.forename: Samir K
authors.initials: SK
authors.lastname: El-Mofty
authors.forename: Tim
authors.initials: T
authors.lastname: Helliwell
authors.forename: Manju L
authors.initials: ML
authors.lastname: Prasad
authors.forename: Ann
authors.initials: A
authors.lastname: Sandison
authors.forename: Metka
authors.initials: M
authors.lastname: Volavšek
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Wenig
authors.forename: Nina
authors.initials: N
authors.lastname: Zidar
authors.forename: Antonio
authors.initials: A
authors.lastname: Cardesa
mesh_terms: D018450:Disease Progression; D004847:Epithelial Cells / Q000473:pathology*; D006801:Humans; D007820:Laryngeal Mucosa / Q000473:pathology*; D007822:Laryngeal Neoplasms / Q000473:pathology*; D060787:Neoplasm Grading / Q000379:methods*; D011230:Precancerous Conditions / Q000145:classification* / Q000473:pathology*; D017524:Slovenia
keywords: amended Ljubljana classification; larynx; proposed unified classification; squamous intraepithelial lesions