[Non-invasive and invasive urothelial tumours: special challenges in uropathological diagnostics].

The current 2004 WHO classification of bladder tumors categorizes non-invasive and invasive urothelial neoplasms into prognostically relevant groups according to the histopathological cell morphology and underlying genetic changes. Although many parts of the classification have not been changed dramatically, even small changes have caused uncertainty and scepticism among urologists and pathologists in recent years. The following review article is structured into various challenges for urologists and pathologists and provides an overview of rare but clinically relevant subgroups and diagnostics, interpretation of diagnoses and pathological findings with respect to consequences for the daily clinical routine (extended diagnosis, therapy and prognosis).