Abstract

The fifth edition of the World Health Organization (WHO) “Blue Book” on urinary and male genital tumours was published in 2022, but since when has the WHO been concerned about the classification of these neoplasms?
It all began in 1952, when the WHO committee of Health Statistics established that, in order to statistically categorise tumours, they had to be classified according to anatomical site, histological type and degree of malignancy. In 1956 the WHO Executive Board proposed organising specific centres to fullfil this project. Following the establishment of these centres in 1958, microscope slides were sent to different pathologists with the purpose of reaching a consensus on classification criteria. The WHO centre for urinary and male genital tumours was the Armed Forces Institute of Pathology (AFIP) in Washington, under the direction of F.K. Mostofi, who was responsible for the first two editions, with separate books dedicated to each organ: Urinary bladder first edition in 1973 ¹, second edition in 1999 ²; Testis first edition in 1977 ³, second edition in 1998 ⁴; Kidney first edition in 1981 ⁵, second edition in 1998 ⁶; and Prostate first edition in 1980 ⁷. No publication covered tumours of the Penis. These volumes provided brief reviews accompanied by coloured illustrations of all recognised neoplasms and their variants.
The third edition, printed in 2004, saw a considerable change ⁸. Firstly, tumours of the various organs of the urinary and male genital systems, including the penis, were gathered in a single book. Secondly, the editors, J.N. Eble, G. Sauter, J.I. Epstein and I.A. Sesterhenn, were from different institutions. Thirdly, the preliminary drafting of tumour types was accomplished by a large number of pathologists from different countries, and a consensus meeting was held at the International Agency for Research on Cancer (IARC) in Lyon, where the book was published.
After a consensus meeting at the University Hospital in Zürich, the fourth edition, edited by H. Moch, P.A. Humphrey, T.M. Ulbright and V.E. Reuter, was released in 2016 and updated the contents following the guidelines set out in the third edition ⁹.
The current edition, published in print as well as a website (htpp://tumourclassification. iarc.who.int) in 2022, can boast an extensive editorial board (M.B. Amin, D.M. Berney, E.M. Comperat, A. Hartmann, S. Menon, G.J. Netto, M.R. Raspollini, M.A. Rubin, S.K. Tickoo and S. Turajlic) that convened via video conference in January 2021, during the Covid-19 pandemic ¹⁰. Updates are provided with a uniform layout for each chapter and individual tumours are described on the basis of clinical features, epidemiology, etiology, pathogenesis, histopathology, diagnostic molecular pathology, staging and prognosis. Information on macroscopy and cytology as well as essential and desirable diagnostic criteria are also included. Another novelty of this edition is specific chapters comcerning genetic tumour syndromes, neuroendocrine neoplasms, mesenchymal and haematolymphoid tumours, most often found in the urinary and male genital tracts.
The evolution of the WHO “Blue Books” is characterised not only by the updating of tumour classifications but also by full coverage of clinical, morphological and molecular genetic data. Without becoming comprehensive textbooks, they are essential tools conveying international standards for diagnosis and cancer research.