[Urine-based tumour diagnostics for bladder cancer: effects of the new histopathological classification--food for thought].

The new WHO classification of bladder cancer was published in 2004 and consequently cannot be regarded as very recent. However, it is still timely since it picks up considerations affecting other schemes of tumour classification as well. Genetic results are included in the context of morphology, and at the same time a high inter- and intra-observer agreement is striven for as a matter of high quality patient care. The WHO classification of 2004 does not include cytological diagnosis. Thinking about and considering tumour tissue diagnosis, the style of cytological diagnoses is also affected. For tissue diagnoses, low- and high-grade tumours are differentiated from benign lesions including reactive changes. The element of this classification which has to be transferred to cytology is especially the unequivocal diagnosis of high-grade lesions. The low-grade lesion, correlating with tissue of well-differentiated papillary tumours and dysplasias, mostly cannot be distinguished cytologically with certainty from a broad spectrum of non-malignant lesions (papillomas, reactive urothelial detachment in urolithiasis patients, cytology specimen from vigorously irrigated bladders). For the latter group our aim should be to establish an additional diagnostic tool of high quality driven by clinical questions (e.g. potential of tumour progression).