Tickoo, Satish K.

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.

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.

Pelvicalyceal invasion (PCI) is a relatively novel pT3a staging parameter for renal cell carcinoma (RCC) nephrectomies. While interobserver reproducibility staging studies of sinus/vascular invasion in RCC exist, a similar evaluation for PCI has not been performed. Moreover, in our experience, there is also diagnostic variability in how pathologists interpret PCI. Herein, we explore interobserver reproducibility among genitourinary (GU) pathologists. Twenty hematoxylin and eosin-stained digitized slides from RCCs (all grossly approaching the renal pelvis) were distributed to 31 GU pathologists to classify each as PCI or not PCI based on their respective clinical practices; slides with concomitant sinus/fat/vascular invasion were excluded. Slides were then evaluated for the following 4 morphologic features: tumor abutting renal pelvis, tumor pushing/indenting into the renal pelvis, polypoid configuration of tumor into the renal pelvis, and tumor eroding through renal pelvic urothelium. Interobserver reproducibility was assessed, and the morphologic features were correlated with PCI. Relationships between pathologists’ interpretations, morphologic features, and PCI were evaluated using hierarchical clustering. Although the diagnosis of PCI was relatively uniform with a majority agreement (>67%) reached in 16/20 slides, overall interobserver reproducibility was only moderate (kappa=0.601). While all 4 morphologic features were sensitive for PCI, polypoid configuration of the tumor into the renal pelvis and the tumor eroding through the renal pelvic urothelium were most specific (90%, 100%, respectively). Although we show general consensus among genitourinary pathologists on PCI assessment, clarifying the diagnostic guidelines with specific criteria should be included in pathologic staging systems.

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).

BACKGROUND: Immune checkpoint inhibitors are an important therapeutic option for urothelial carcinoma, but durable responses are achieved in a minority of patients. Identifying pre-treatment biomarkers that may predict response to these therapies or who exhibit intrinsic resistance, is of paramount importance. OBJECTIVE: To explore the prevalence of PD-L1 copy number alteration in urothelial carcinoma and correlate with response to immune checkpoint inhibitors. METHODS: We analyzed a cohort of 1050 carcinomas of the bladder and upper urinary tract that underwent targeted next generation sequencing, prospectively. We assessed PD-L1 protein expression, copy number status (next generation sequencing/FISH), and detailed treatment response. RESULTS: We identified 9 tumors with PD-L1 amplification and 9 tumors with PD-L1 deletion. PD-L1 protein expression was the highest in PD-L1 amplified tumors. Of the 9 patients whose tumors harbored PD-L1 amplification, 6 received immunotherapy with 4 deriving clinical benefit, and 2 achieving durable response. Of the 9 patients whose tumors had PD-L1 copy number losses, 4 received immunotherapy with 3 experiencing disease progression. CONCLUSIONS: PD-L1 copy number alterations may serve as potential biomarkers of response to immunotherapy in urothelial carcinoma patients, if validated in larger cohorts.

Transcription factor E3-rearranged renal cell carcinoma (TFE3-RCC) has heterogenous morphologic and immunohistochemical (IHC) features. 131 pathologists with genitourinary expertise were invited in an online survey containing 23 questions assessing their experience on TFE3-RCC diagnostic work-up. Fifty (38%) participants completed the survey. 46 of 50 participants reported multiple patterns, most commonly papillary pattern (almost always 9/46, 19.5%; frequently 29/46, 63%). Large epithelioid cells with abundant cytoplasm were the most encountered cytologic feature, with either clear (almost always 10/50, 20%; frequently 34/50, 68%) or eosinophilic (almost always 4/49, 8%; frequently 28/49, 57%) cytology. Strong (3+) or diffuse (>75% of tumour cells) nuclear TFE3 IHC expression was considered diagnostic by 13/46 (28%) and 12/47 (26%) participants, respectively. Main TFE3 IHC issues were the low specificity (16/42, 38%), unreliable staining performance (15/42, 36%) and background staining (12/42, 29%). Most preferred IHC assays other than TFE3, cathepsin K and pancytokeratin were melan A (44/50, 88%), HMB45 (43/50, 86%), carbonic anhydrase IX (41/50, 82%) and CK7 (32/50, 64%). Cut-off for positive TFE3 fluorescent in situ hybridisation (FISH) was preferably 10% (9/50, 18%), although significant variation in cut-off values was present. 23/48 (48%) participants required TFE3 FISH testing to confirm TFE3-RCC regardless of the histomorphologic and IHC assessment. 28/50 (56%) participants would request additional molecular studies other than FISH assay in selected cases, whereas 3/50 participants use additional molecular cases in all cases when TFE3-RCC is in the differential. Optimal diagnostic approach on TFE3-RCC is impacted by IHC and/or FISH assay preferences as well as their conflicting interpretation methods.

Chromophobe renal cell carcinoma (chRCC) typically shows ~7 chromosome losses (1, 2, 6, 10, 13, 17, and 21) and ~31 exonic somatic mutations, yet carries ~5%–10% metastatic incidence. Since extensive chromosomal losses can generate proteotoxic stress and compromise cellular proliferation, it is intriguing how chRCC, a tumor with extensive chromosome losses and a low number of somatic mutations, can develop lethal metastases. Genomic features distinguishing metastatic from nonmetastatic chRCC are unknown. An integrated approach, including whole-genome sequencing (WGS), targeted ultradeep cancer gene sequencing, and chromosome analyses (FACETS, OncoScan, and FISH), was performed on 79 chRCC patients including 38 metastatic (M-chRCC) cases. We demonstrate that TP53 mutations (58%), PTEN mutations (24%), and imbalanced chromosome duplication (ICD, duplication of ≥ 3 chromosomes) (25%) were enriched in M-chRCC. Reconstruction of the subclonal composition of paired primary-metastatic chRCC tumors supports the role of TP53 , PTEN , and ICD in metastatic evolution. Finally, the presence of these 3 genomic features in primary tumors of both The Cancer Genome Atlas kidney chromophobe (KICH) ( n = 64) and M-chRCC ( n = 35) cohorts was associated with worse survival. In summary, our study provides genomic insights into the metastatic progression of chRCC and identifies TP53 mutations, PTEN mutations, and ICD as high-risk features.

513 Background: Chromophobe renal cell carcinoma (chRCC) is the third most common histologic subtype of kidney cancer. While most of these tumors have an indolent behavior, 7% of patients with chRCC develop metastases, with no currently available standard of care. The Cancer Genome Atlas characterized chRCC, highlighting pathognomonic single copy chromosomal losses of 1, 2, 6, 10, 13 and 17, as well as a minimal mutation burden distinguishing it from all other cancer types. However, only 15% of the analyzed patients had advanced disease. We analyzed metastatic chRCC to further characterize these tumors and elucidate mechanisms leading to aggressive disease using a variety of next generation and whole genome sequencing. Methods: Our cohort of metastatic chRCC consisted of 40 patients with available clinical and pathologic data. Whole genome sequencing (WGS) was performed on 6 patients (4 primary tumors and 2 metastases), 42 additional samples from 33 patients were analyzed using targeted next-generation sequencing (MSK-IMPACT). Notably, we were able to collect and analyze matched primary and metastatic tumors from 7 patients. As control cohort 27 non-metastatic chRCC tumors were sequenced with MSK-IMPACT. Copy number patterns were computed with OncoSNP seq and FACETS. Results: The most commonly mutated genes in the aggressive chRCC tumors were TP53 and PTEN (WGS: TP53 67 %, PTEN 33%; MSK-IMPACT: TP53 61%, PTEN 27%). No other genes were mutated frequently. Primary tumor samples of chRCC did show the typical pattern of chromosomal losses in 1, 2, 6, 10, 13 and 17. Interestingly, these canonical losses could not be detected in the metastases even when accounting for tumor purity. Conclusions: TP53 and PTEN mutations are highly enriched in both primary and metastatic tumors of aggressive chRCC compared to the non-aggressive tumors and likely play a critical role in disease progression. More intriguingly, the observation of differential copy numbers in matched primary and metastatic tumors suggest whole genome or whole chromosome events in these samples. We are currently employing different bioinformatic and cytogenetic platforms to validate our novel hypothesis of chromosomal events as driver for metastatic development in chRCC.