[Papilloma of urinary bladder according to the WHO-classification. A critical contribution to morphological diagnostics (author's transl)].

Reclassification of 1905 bladder tumors out of a total of 2845 bladder biopsies revealed that only 47, i.e. 2.5% could be classified as papillomas according to the WHO-classification. The reasons for former uncertain classification of low grade papillary bladder tumors and the advantage of clear morphological classifications are discussed on the basis of 283 tumors which were temporarily classified as border line cases and finally as G1-pTA-tumors according to the WHO- and UICC-definition.