Tsuzuki, Toyonori

Aims Testicular sex cord‐stromal tumours (TSCSTs) are rare neoplasms that arise from (or show differentiation to) elements derived from the sex cords or intertubular stroma. The current classification (World Health Organization, 2022) is based almost entirely on morphology, with many tumour types such as granulosa cell tumours being defined based on their resemblance to ovarian counterparts. Recent studies have uncovered new clinicopathological, molecular and biological nuances within this group of tumours, underscoring differences with ovarian homologues. Methods and results Considering the new data, a group of genitourinary pathology experts (Testicular Sex Cord‐Stromal Tumour [TESST] group) has proposed a revised ‘TESST classification’ that incorporates the best available evidence. This classification is structured and hierarchical, composed of the following tiers: (1) group, (2) category, (3) entity and (4) histological pattern. ‘Group’ refers to the histological compartment a specific tumour belongs to (sex cords, stroma or both), whereas ‘category’ is defined by the phenotype of the tumour, taking non‐neoplastic elements of the ovary and testis as a reference. The third tier, ‘entity’, refers to neoplasms with shared clinicopathological and/or molecular features that justify classifying them as distinct types. Lastly, ‘histological patterns’ are recurrent morphological variations within entities that are not linked to distinct clinicopathological or molecular features. Conclusions We propose a classification that will provide a framework to improve current clinical management and guide future research in the field.

Aims Testicular sex cord‐stromal tumours (TSCSTs) are relatively rare, accounting for ~5% of all testicular neoplasms. They were historically classified into Leydig cell tumour, Sertoli cell tumour, granulosa cell tumour, and unclassified sex cord‐stromal tumour. More recently, classification was expanded to incorporate additional histologic types, including some associated with inherited cancer predisposition syndromes. However, the classification of TSCSTs still relies entirely on morphology, with some tumour types being defined based on their resemblance to ovarian counterparts. In recent years, molecular studies have identified drivers and genomic alterations associated with aggressive behaviour and progression; however, these findings have not yet impacted classification and management. Methods and results Under sponsorship of the International Society of Urological Pathology (ISUP) and the Genitourinary Pathology Society (GUPS), a group of genitourinary pathologists was assembled in 2023 with the aim of assessing how to use these new data to improve the classification and management of TSCSTs. Conclusions This paper summarizes the recommendations derived from the consensus activities and the first meeting of the te sticular s ex cord‐ s tromal t umour (TESST) group (held at Johns Hopkins Hospital, Baltimore, USA, 3/23/2024).

AimsDespite efforts to standardise grading of prostate cancer, even among experts there is still a considerable variation in grading practices. In this study we describe the use of Pathology Imagebase, a novel reference image library, for setting an international standard in prostate cancer grading.Methods and resultsThe International Society of Urological Pathology (ISUP) recently launched a reference image database supervised by experts. A panel of 24 international experts in prostate pathology reviewed independently microphotographs of 90 cases of prostate needle biopsies with cancer. A linear weighted kappa of 0.67 (95% confidence interval = 0.62–0.72) and consensus was reached in 50 cases. The interobserver weighted kappa varied from 0.48 to 0.89. The highest level of agreement was seen for Gleason score (GS) 3 + 3 = 6 (ISUP grade 1), while higher grades and particularly GS 4 + 3 = 7 (ISUP grade 3) showed considerable disagreement. Once a two‐thirds majority was reached, images were moved automatically into a public database available for all ISUP members at www.isupweb.org. Non‐members are able to access a limited number of cases.ConclusionsIt is anticipated that the database will assist pathologists to calibrate their grading and, hence, decrease interobserver variability. It will also help to identify instances where definitions of grades need to be clarified.

AimsDespite efforts to standardize histopathology practice through the development of guidelines, the interpretation of morphology is still hampered by subjectivity. We here describe Pathology Imagebase, a novel mechanism for establishing an international standard for the interpretation of pathology specimens.Methods and resultsThe International Society of Urological Pathology (ISUP) established a reference image database through the input of experts in the field. Three panels were formed, one each for prostate, urinary bladder and renal pathology, consisting of 24 international experts. Each of the panel members uploaded microphotographs of cases into a non‐public database. The remaining 23 experts were asked to vote from a multiple‐choice menu. Prior to and while voting, panel members were unable to access the results of voting by the other experts. When a consensus level of at least two‐thirds or 16 votes was reached, cases were automatically transferred to the main database. Consensus was reached in a total of 287 cases across five projects on the grading of prostate, bladder and renal cancer and the classification of renal tumours and flat lesions of the bladder. The full database is available to all ISUP members at www.isupweb.org. Non‐members may access a selected number of cases.ConclusionsIt is anticipated that the database will assist pathologists in calibrating their grading, and will also promote consistency in the diagnosis of difficult cases.