Srigley, John R.

According to the current WHO classification, noninvasive germ cell neoplasia of the testis comprises germ cell neoplasia in situ (GCNIS), specific forms of intratubular germ cell neoplasia, and gonadoblastoma. Because type II germ cell tumors (GCT, type II) arise from GCNIS, accurate detection of precursor lesions is diagnostically important. In preparation for the 2024 International Society of Urological Pathology (ISUP) Consensus Conference on genitourinary precursor lesions, which took place in Florence, Italy, an anonymous survey was distributed to ISUP members to assess current diagnostic practices regarding testicular precursor lesions. The literature and current WHO classification affirm the significance of precursor lesions in testicular tumours. Working Group 4—Precursor Lesions of the Testis—focused on their practical application by individual pathologists rather than establishing consensus from scientific data. There is strong agreement that GCNIS is the preferred and appropriate term for GCT precursor lesions and that its presence should be reported in cases of invasive GCT. Respondents also agree that “seminoma with intratubular nonseminoma” is the appropriate terminology for seminoma with an associated noninvasive nonseminomatous (embryonal carcinoma, yolk sac tumor, trophoblasts, or teratoma) component. Most pathologists prefer to use OCT3/4 as the primary immunohistochemical marker, and a panel was generally not considered necessary. No consensus is reached regarding the requirement for immunohistochemistry to confirm GCT precursor lesions in the testis. Three questions remain open: the value of subtyping intratubular lesions, the immunohistochemical approach to gonadoblastoma, and the criteria distinguishing Sertoli cell nodules from Sertoli cell tumors.

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.