Interobserver variability of laryngeal mucosal premalignant lesions: a histopathological evaluation

The objective of this study is to measure interobserver variability in the classification of laryngeal mucosal premalignant lesions by reassessing the histopathology of previously diagnosed cases and to determine the possible therapeutic consequences of disagreement among observers. Histopathological assessment of 110 laryngeal mucosal premalignant lesions was done by three pathologists. Each slide had to be classified according to the World Health Organization, Squamous Intraepithelial Neoplasia, and the Ljubljana Squamous Intraepithelial Lesions systems. After the independent assessment, a joint meeting took place. To assess the relation between histopathological grading and subsequent clinical management, we created a two-and a three-grade system besides one comprising all options. For all analyses, the SAS/STAT statistical software was used. The highest unweighted kappa-values concerning the all-options system are observed for the Squamous Intraepithelial Neoplasia classification (0.28, 95% confidence interval 0.23-0.33), followed by the World Health Organization and Ljubljana classifications. For the two-grade system the Ljubljana classification shows the highest unweighted kappa-values (0.50, 95%, 0.39-0.61), followed by the World Health Organization and Squamous Intraepithelial Neoplasia classifications. For the three-grade system, the unweighted kappa-values are similar. The implementation of weighted kappa-values led to higher scores within all three classification systems, although these did not exceed 0.55 (moderate agreement). Given the high level of consensus, simultaneous pathological assessment may be said to provide added value in comparison with independent assessment. In the current study, no clear tendency is observed in favor of any one classification system. The proposed three-grade system could be an improved histopathological tool because it is easier to correlate with clinical decision making and because it yields better unweighted kappa-values and proportions of concordance than the all-options system. Furthermore, clinical management could benefit from assessment by more than one pathologist in suspected cases of dysplasia or carcinoma. Modern Pathology (2011) 24, 892-898; doi: 10.1038/modpathol.2011.50; published online 15 April 2011