UROTHELIAL NEOPLASIA OF THE URINARY BLADDER – COMPARISON OF INTEROBSERVER VARIABILITY FOR WHO CLASSIFICATION 1972 WITH WHO/ISUP CONSENSUS CLASSIFICATION 1998
AbstractBackground: Classification of urothelial bladder tumours is an important factor in the treatmentand prognosis of these lesions. Over the years many classifications have been proposed for thispurpose. The objective of this study was to classify urothelial neoplasms of the urinary bladderusing the latest WHO/ ISUP Consensus Classification 1998 and WHO Classification 1972 andcompare the two regarding interobserver variability. Methods: This study included 100consecutive biopsy specimens of urothelial neoplasms of the urinary bladder diagnosed at thedepartment of Histopathology, Armed Forces Institute of Pathology, Rawalpindi. These wereclassified according to WHO Classification 1972 and WHO/ISUP Consensus Classification 1998by 2 groups of pathologists independently. The tumour categories for WHO classification 1972;papilloma, and transitional cell carcinoma (TCC) grades I, II and III were compared with theWHO/ISUP Consensus Classification entities of papilloma, papillary neoplasm of low malignantpotential, low grade and high grade papillary carcinomas. Kappa statistics were used to evaluateinterobserver variability. Chi square test was used to calculate significance. Results: There wasagreement on 80 tumours between the two groups of histopathologists when using WHOclassification 1972 while there was agreement on 95 tumours using WHO/ISUP consensusclassification. The value of Kappa for WHO Classification was 0.68 (good agreement) whereas forWHO/ISUP Consensus Classification it was 0.91 (excellent agreement). The difference betweenthe two systems was statistically significant (p<0.001). Kappa values were less for benign andborderline lesions using both systems. Conclusions: WHO/ISUP Consensus Classification 1998showed less interobserver variability than WHO Classification 1972 in the evaluation of bladdertumours . It was found easier to apply by both groups. There was less agreement on the benign andborderline lesions using both the classifications.Key Words: Transitional cell carcinoma, Urinary bladder neoplasms, Urothelial neoplasia.
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