Reproductibilité des classifications OMS 1973 et OMS 2004 des tumeurs urothéliales papillaires de la vessie

摘要

Aims: To assess the diagnostic agreement and intra- and inter-observer reproducibility of the 1973 and the 2004 World Health Organization (WHO) classifications of Urothelial Papillary Neoplasms of the bladder. Methods: One hundred and two cases of pTa/pT1 papillary urothelial bladder tumours were evaluated retrospectively. Two pathologists reviewed the slides and assigned a tumour grade according to the 1973 and the 2004 WHO classifications. Whenever a discrepancy was noted between the first and the second reading, the two pathologists together reviewed the slides and reached a consensus for the final grading according to the two classifications. Intra-observer variability was assessed by one of the two pathologists who reviewed the slides one month later. Interpretive discrepancies for each category of neoplasm were documented. Degree of agreement and reproducibility were evaluated using intra- and inter-rater techniques (kappa statistic). A value of 0.21–0.40 was accepted as weak, 0.41–0.60 as moderate, 0.61–0.80 as substantial and 0.81–1 as absolute agreement. Results: According to the 1973 WHO classification, the proportions of G1, G2 and G3 tumours were 40.2%, 50% and 9.8%, respectively. According to the 2004 WHO classification, the proportions of tumours of low malignant potential, low-grade carcinomas, and high-grade carcinomas were 23.5%, 60.8% and 15.7%, respectively. The intra-observer reproducibility was excellent for the two classifications (absolute agreement). The degree of agreement between pathologists was higher in the 2004 WHO (kappa = 0.7) than the 1973 WHO classification (kappa = 0.51). Conclusions: The present findings suggest that the new proposed classification system for urothelial papillary neoplasms slightly increases the inter-observer reproducibility. The intra-observer reproducibility is excellent for the two classifications.