WHO Classification Of Tumours Of The Urinary System And Male Genital Organs (IARC WHO Classification
Urinary and Male Genital Tumours is Volume 8 in the 5th edition of the WHO series on the classification of human tumours. This series (also known as the WHO Blue Books) is regarded as the gold standard for the diagnosis of tumours and comprises a unique synthesis of histopathological diagnosis with digital and molecular pathology. These authoritative and concise reference books provide indispensable international standards for anyone involved in the care of patients with cancer or in cancer research, underpinning individual patient treatment as well as research into all aspects of cancer causation, prevention, therapy, and education.
WHO Classification of Tumours of the Urinary System and Male Genital Organs (IARC WHO Classification
The 5th edition, guided by the WHO Classification of Tumours Editorial Board, will establish a single coherent cancer classification presented across a collection of individual volumes organized on the basis of anatomical site (digestive system, breast, soft tissue and bone, etc.) and structured in a systematic manner, with each tumour type listed within a taxonomic classification: site, category, family (class), type, and subtype. In each volume, the entities are now listed from benign to malignant and are described under an updated set of headings, including histopathology, diagnostic molecular pathology, staging, and easy-to-read essential and desirable diagnostic criteria.
Urinary and Male Genital Tumours is Volume 8 in the 5th edition of the World Health Organization (WHO) series on the classification of human tumours. This series (also known as the WHO Blue Books) is regarded as the gold standard for the diagnosis of tumours and comprises a unique synthesis of histopathological diagnosis with digital and molecular pathology.
The fourth edition of the World Health Organization (WHO) classification of urogenital tumours (WHO "blue book"), published in 2016, contains significant revisions. These revisions were performed after consideration by a large international group of pathologists with special expertise in this area. A subgroup of these persons met at the WHO Consensus Conference in Zurich, Switzerland, in 2015 to finalize the revisions. This review summarizes the most significant differences between the newly published classification and the prior version for renal, penile, and testicular tumours. Newly recognized epithelial renal tumours are hereditary leiomyomatosis and renal cell carcinoma (RCC) syndrome-associated RCC, succinate dehydrogenase-deficient RCC, tubulocystic RCC, acquired cystic disease-associated RCC, and clear cell papillary RCC. The WHO/International Society of Urological Pathology renal tumour grading system was recommended, and the definition of renal papillary adenoma was modified. The new WHO classification of penile squamous cell carcinomas is based on the presence of human papillomavirus and defines histologic subtypes accordingly. Germ cell neoplasia in situ (GCNIS) of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours, and testicular germ cell tumours are now separated into two fundamentally different groups: those derived from GCNIS and those unrelated to GCNIS. Spermatocytic seminoma has been designated as a spermatocytic tumour and placed within the group of non-GCNIS-related tumours in the 2016 WHO classification.
Patient summary: The 2016 World Health Organization (WHO) classification contains new renal tumour entities. The classification of penile squamous cell carcinomas is based on the presence of human papillomavirus. Germ cell neoplasia in situ of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours.
It has been 12 yr since the publication of the last World Health Organization (WHO) classification of tumours of the prostate and bladder. During this time, significant new knowledge has been generated about the pathology and genetics of these tumours. Intraductal carcinoma of the prostate is a newly recognized entity in the 2016 WHO classification. In most cases, it represents intraductal spread of aggressive prostatic carcinoma and should be separated from high-grade prostatic intraepithelial neoplasia. New acinar adenocarcinoma variants are microcystic adenocarcinoma and pleomorphic giant cell adenocarcinoma. Modifications to the Gleason grading system are incorporated into the 2016 WHO section on grading of prostate cancer, and it is recommended that the percentage of pattern 4 should be reported for Gleason score 7. The new WHO classification further recommends the recently developed prostate cancer grade grouping with five grade groups. For bladder cancer, the 2016 WHO classification continues to recommend the 1997 International Society of Urological Pathology grading classification. Newly described or better defined noninvasive urothelial lesions include urothelial dysplasia and urothelial proliferation of uncertain malignant potential, which is frequently identified in patients with a prior history of urothelial carcinoma. Invasive urothelial carcinoma with divergent differentiation refers to tumours with some percentage of "usual type" urothelial carcinoma combined with other morphologies. Pathologists should mention the percentage of divergent histologies in the pathology report.
The fifth edition of the World Health Organization (WHO) classification of urogenital tumours (WHO "Blue Book"), published in 2022, contains significant revisions. This review summarises the most relevant changes for renal, penile, and testicular tumours. In keeping with other volumes in the fifth edition series, the WHO classification of urogenital tumours follows a hierarchical classification and lists tumours by site, category, family, and type. The section "essential and desirable diagnostic criteria" included in the WHO fifth edition represents morphologic diagnostic criteria, combined with immunohistochemistry and relevant molecular tests. The global introduction of massive parallel sequencing will result in a diagnostic shift from morphology to molecular analyses. Therefore, a molecular-driven renal tumour classification has been introduced, taking recent discoveries in renal tumour genomics into account. Such novel molecularly defined epithelial renal tumours include SMARCB1-deficient medullary renal cell carcinoma (RCC), TFEB-altered RCC, Alk-rearranged RCC, and ELOC-mutated RCC. Eosinophilic solid and cystic RCC is a novel morphologically defined RCC entity. The diverse morphologic patterns of penile squamous cell carcinomas are grouped as human papillomavirus (HPV) associated and HPV independent, and there is an attempt to simplify the morphologic classification. A new chapter with tumours of the scrotum has been introduced. The main nomenclature of testicular tumours is retained, including the use of the term "germ cell neoplasia in situ" (GCNIS) for the preneoplastic lesion of most germ cell tumours and division from those not derived from GCNIS. Nomenclature changes include replacement of the term "primitive neuroectodermal tumour" by "embryonic neuroectodermal tumour" to separate these tumours clearly from Ewing sarcoma. The term "carcinoid" has been changed to "neuroendocrine tumour", with most examples in the testis now classified as "prepubertal type testicular neuroendocrine tumour".
The classification of neuroendocrine neoplasms (NENs) differs between organ systems and currently causes considerable confusion. A uniform classification framework for NENs at any anatomical location may reduce inconsistencies and contradictions among the various systems currently in use. The classification suggested here is intended to allow pathologists and clinicians to manage their patients with NENs consistently, while acknowledging organ-specific differences in classification criteria, tumor biology, and prognostic factors. The classification suggested is based on a consensus conference held at the International Agency for Research on Cancer (IARC) in November 2017 and subsequent discussion with additional experts. The key feature of the new classification is a distinction between differentiated neuroendocrine tumors (NETs), also designated carcinoid tumors in some systems, and poorly differentiated NECs, as they both share common expression of neuroendocrine markers. This dichotomous morphological subdivision into NETs and NECs is supported by genetic evidence at specific anatomic sites as well as clinical, epidemiologic, histologic, and prognostic differences. In many organ systems, NETs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, and/or the presence of necrosis; NECs are considered high grade by definition. We believe this conceptual approach can form the basis for the next generation of NEN classifications and will allow more consistent taxonomy to understand how neoplasms from different organ systems inter-relate clinically and genetically.
The current pathologic classifications of neuroendocrine neoplasms (NENs) across different organ systems use a range of site-specific terminologies and criteria, creating significant confusion among pathologists and treating clinicians. The World Health Organization (WHO) International Agency for Research on Cancer (IARC) has now started the new fifth edition of the WHO Classification of Tumors, published as the widely used WHO Blue Books ( ). A uniform classification framework for NENs at any anatomical location would reduce inconsistencies and contradictions among the various systems currently in use, allowing unification of classification concepts, despite organ-specific differences in classification criteria, tumor biology, and prognostic factors. The classification suggested here is intended to allow pathologists and clinicians to manage their patients with NENs consistently, and to facilitate comparisons between the different entities falling into this category of neoplasms.
Existing classification systems vary widely in terminology and criteria between sites, with robust data supporting grading systems in some anatomic sites (e.g., lung, gastrointestinal tract, pancreas), but not in others (e.g., breast, thyroid, parathyroid). In addition, some NETs have been subjected to careful cell-type classification (most well-known in the pituitary, but also in the rectum and pancreas) that has prognostic and predictive value, whereas others have not, e.g., in the female genital tract and breast. The relative prevalence of different NEN categories also varies by anatomic site. The panorama of genetic knowledge regarding NENs is patchy, with well-defined traits defined by high-throughput studies for some anatomic sites and relatively scarce information for other sites.