Nadira Mamoon, Muhammad Ashraf Iqbal, Shahid Jamal, Muhammad Luqman


Background: Classification of urothelial bladder tumours is an important factor in the treatment
and prognosis of these lesions. Over the years many classifications have been proposed for this
purpose. The objective of this study was to classify urothelial neoplasms of the urinary bladder
using the latest WHO/ ISUP Consensus Classification 1998 and WHO Classification 1972 and
compare the two regarding interobserver variability. Methods: This study included 100
consecutive biopsy specimens of urothelial neoplasms of the urinary bladder diagnosed at the
department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi. These were
classified according to WHO Classification 1972 and WHO/ISUP Consensus Classification 1998
by 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 the
WHO/ISUP Consensus Classification entities of papilloma, papillary neoplasm of low malignant
potential, low grade and high grade papillary carcinomas. Kappa statistics were used to evaluate
interobserver variability. Chi square test was used to calculate significance. Results: There was
agreement on 80 tumours between the two groups of histopathologists when using WHO
classification 1972 while there was agreement on 95 tumours using WHO/ISUP consensus
classification. The value of Kappa for WHO Classification was 0.68 (good agreement) whereas for
WHO/ISUP Consensus Classification it was 0.91 (excellent agreement). The difference between
the two systems was statistically significant (p<0.001). Kappa values were less for benign and
borderline lesions using both systems. Conclusions: WHO/ISUP Consensus Classification 1998
showed less interobserver variability than WHO Classification 1972 in the evaluation of bladder
tumours . It was found easier to apply by both groups. There was less agreement on the benign and
borderline lesions using both the classifications.
Key Words: Transitional cell carcinoma, Urinary bladder neoplasms, Urothelial neoplasia.

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