I.A. Sesterhenn – författare

This classification is based primarily on the microscopic characteris- tics of tumours and therefore is concerned with morphologically identifiable cell types and histological patterns as seen with conven- tional light microscopy. The term tumour is used synonymously with neoplasm. The phrase tumour-like is applied to lesions that clinically or morpholog- ically resemble neoplasms but do not behave biologically in a neo- plastic manner. They are included in this publication because they give rise to problems in differential diagnosis and because of the un- clear distinction between neoplasms and certain non-neoplastic le- sions. Synonyms are listed only if they have been widely used or are considered helpful for the understanding of the lesion. In such cases, the preferred term is given first and followed by the synonym. The current revision includes the recognition of a preinvasive le- sion, prostatic intraepithelial neoplasia, which is commonly associat- ed with carcinoma. It also recognises the paracrine-endocrine ele- ments in prostate carcinoma and other subtypes of adenocarcinoma.Although the emphasis of the classification is on histological typ- ing, consideration should also be given to the degree of differentia- tion and nuclear anaplasia, extent of local spread, vascular and lym- phatic invasion, and the occurrence of metastasis. The revision in- cludes grading (p. 14), staging (p. 32), and handling and reporting of the different types of specimens (p. 1).

The 1973 WHO classification of bladder tumours anticipated a probable need for eventual revision of the criteria for diagnosing papillary and flat bladder neoplasia. A workshop sponsored by the WHO consisting of pathologists, urologists, cytologists, oncologists and basic scientists interested in bladder tumours addressed this subject, and after a follow- -up meeting sponsored by the International Society of Urological Pathology, the classification and terminology used in this text were agreed upon. A major change is in the introduction of a new category: papillary urothelial neoplasm of low malignant potential. Many of the tumours previously designated as papillary transitional cell carcinoma, grade I now fall into that category. Another major change is in the designation of flat lesions, and this includes a definition of carcinoma in situ. Furthermore, a number of variant forms of urothelials carcinomas are included as well as new entities not recognized when the 1st edition was issued.

The 1973 WHO classification of bladder tumours anticipated a probable need for eventual revision of the criteria for diagnosing papillary and flat bladder neoplasia. A workshop sponsored by the WHO consisting of pathologists, urologists, cytologists, oncologists and basic scientists interested in bladder tumours addressed this subject, and after a follow- -up meeting sponsored by the International Society of Urological Pathology, the classification and terminology used in this text were agreed upon. A major change is in the introduction of a new category: papillary urothelial neoplasm of low malignant potential. Many of the tumours previously designated as papillary transitional cell carcinoma, grade I now fall into that category. Another major change is in the designation of flat lesions, and this includes a definition of carcinoma in situ. Furthermore, a number of variant forms of urothelials carcinomas are included as well as new entities not recognized when the 1st edition was issued.