Evaluation of histological malignant stages of epithelial bladder tumours: a simplified classification

A simplified practical histological classification of four stages of bladder epithelial tumours is proposed in accordance with the terminology adopted by WHO. The structural characters of neoplastic elements are considered with respect to their relations with the basal membrane delimiting the epithelia. This criterion gives valid information regarding real malignancy of the tumour and may be applied to biopsies obtained endoscopically. This is very important not only with regard to prognosis but also to therapeutic indications.