Citations

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.

Abstract Introduction: Clinical staging of multifocal non-small cell lung cancer (NSCLC) is facilitated by comparative genomic analysis of separate tumor nodules, but the role of genome-wide copy number profiling for this purpose is uncertain. Methods: We analyzed single nucleotide variants (SNVs), gene fusions, small copy number variants (gene amplifications and homozygous deletions) (sCNVs), and large-scale copy number variants (lCNVs) in a retrospective cohort of 34 patients with >1 lung cancer nodule tested on a previously validated tumor-only 515-gene next generation sequencing (NGS) panel (MayoComplete Solid Tumor Panel). For patients with <2 shared SNVs, a Bayesian approach was formulated to calculate the probability of shared versus independent events occurring in different tumor nodules in the same patient. The prevalence of specific lCNVs in NSCLC was derived from an independent dataset of 100 NSCLC peers tested by the same panel, and the prevalence of SNVs, fusions, and sCNVs in NSCLC was derived from publicly available data. Alterations unique to different tumor nodules and suspected germline alterations were excluded from the Bayesian analysis. Results: There were 54 total comparisons for 34 patients. Eleven of the patients (32.4%) had >=2 shared SNVs along with one or more shared lCNVs also identified in each patient. Eight patients (23.5%) had no shared SNVs, gene fusions, sCNVs, or lCNVs. Using the Bayesian approach for the remaining fifteen (44.1%) patients with at least one shared alteration (SNVs, sCNVs, and lCNVs), the probability of clonal relatedness ranged from 73% for a shared whole arm or whole chromosome lCNV to >99% for tumors with two or more shared alterations including multiple or complex lCNVs and SNVs. Whole chromosome or whole arm lCNVs were sometimes shared between tumor nodules with different driver SNVs. Conclusions: Incorporating lCNVs into comparative genomic analysis provides additional evidence of clonal relatedness in a subset of multifocal NSCLCs. However, differences in bioinformatics pipelines for calling lCNVs, concerns over the imprecision of genome-wide copy number profiling, and uncertainty regarding the temporal relationship between lCNVs and carcinogenesis (including somatic events possibly related to “field cancerization”) create challenges for integrating lCNVs into comparative genomic analysis with standard clinical workflows for tumor-only NGS on paraffin embedded tissue sections. Our simplified approach mitigates some of the uncertainty introduced by incorporating lCNVs into clonality determination. Citation Format: Claire Teigen, Ying-Chun Lo, Sounak Gupta, Stephanie Smoley, Beth Pitel, Hussam Al Kateb, Gopi Sivasankaran, Benjamin Kipp, Ande Rumilla, Gang Zheng, Kevin Halling, Katherine Geiersbach, . A Bayesian framework for evaluating somatic copy number variants into comparative genomic analysis of multifocal non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5423.

Abstract Objectives Sarcomatoid urothelial carcinoma (sUC) is associated with poor clinical outcomes. Herein, we evaluated clinicopathologic features (including PD-L1 expression) for institutional cases. Methods Sixty-five patients with sUC treated by radical cystectomy were matched for age, sex, and pathologic stage to 190 patients with pure urothelial carcinoma (UC). Outcomes were evaluated using the Kaplan-Meier method. Immunohistochemistry (IHC) results for tumor-specific PD-L1 expression in sUC were quantified using H-scores (range, 0-300). Cases with constitutive PD-L1 expression (cPD-L1; H-score ≥240) were evaluated for amplification events using fluorescence in situ hybridization (n = 28), mate-pair sequencing (Mpseq; n = 6), RNA sequencing (n = 5), and targeted next-generation sequencing (n = 8). PD-L1 regulatory pathways were evaluated using gene set enrichment analysis in the Cancer Hallmark dataset. Results Most patients with sUC had advanced disease (≥pT2, 62/65, 95%), without significant differences in overall and cancer-specific survival, when matched to pure UC. Median PD-L1 H-scores using different clones were 100 (SP142), 120 (SP263), and 195 (22C3). cPD-L1 was seen in 43% (28/65) of cases of sUC that were enriched for TP53, TERT, and CDKN2A/B alterations. PD-L1 amplification was identified in 7 (of 28, 25%) of these cases. Bionformatics analysis consistently identified IL6-JAK-STAT3 and interferon α/γ signaling in sUC with cPD-L1 expression. Conclusions Our results suggest that cPD-L1 expression in most sUC occurs secondary to IL6-JAK-STAT3 and interferon α/γ signaling. This provides a biologic rationale for evaluating response to immunotherapy in this patient population.

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.

ABSTRACT Background Li Fraumeni syndrome (LFS) is a hereditary multi‐cancer syndrome caused by alterations in TP53 (MIM# 151623). Next generation sequencing (NGS) allows for the detection of TP53 variants at lower variant allele frequencies (VAFs). A TP53 variant with a VAF < 50% may represent mosaic LFS, aberrant clonal expansion (ACE), or possible circulating tumor DNA. Differentiation among these conditions is important for optimal patient management. Methods Genetic testing was performed using a custom gene panel, with an average read depth of 350× (range 166–553×). DNA extracted from four different tissues (blood, saliva, cultured skin fibroblasts, and colon) was sequenced. Results Here, we describe an adult female patient with a history of an adrenocortical neoplasm and osteosarcoma, diagnosed at 2 and 16 years of age, respectively. Testing of peripheral blood identified a pathogenic TP53 variant, c.733G>A, p.(Gly245Ser) (NM_000546.6); however, subsequent in vitro fertilization with preimplantation genetic testing for monogenic disorders (PGT‐M) did not identify this TP53 variant in any of nine embryos tested. Testing for possible mosaicism in the proband was performed on four different specimens, revealing variable VAFs of the TP53 variant (saliva: 44%; blood: 31%; cultured skin fibroblasts: 18%; and colon tissue: 9%). These results suggest a post‐zygotic event, consistent with mosaic LFS rather than ACE. Conclusion This case highlights the complexity of interpreting mosaic variants in the TP53 gene, and we propose a testing algorithm to aid in the delineation of this phenomenon when relaying cancer and reproductive risk information in the context of mosaicism.

Changes in the nomenclature and classification of adrenal gland diseases are the result of advances in understanding the pathogenesis, germline susceptibility and the clonal‐neoplastic nature of diseases of the adrenal gland. Although numerous classification systems have been proposed, the Weiss system remains the standard for distinguishing benign from malignant adult adrenal cortical tumours, but the Helsinki system and the reticulin algorithm are proving to be increasingly useful in difficult cases. Subtypes of adrenal cortical neoplasms, such as myxoid and oncocytic, as well as those occurring in children require special consideration as their classification systems are different from those for standard adult adrenal cortical neoplasms. The importance of proliferative activity is central to the evaluation of adrenal cortical neoplasms. As for primary unilateral aldosteronism, CYP11B2 immunostain is increasingly studied to identify sites of aldosterone production with the hope of finding staining patterns predictive of clinical outcomes. Awareness of the clonal‐neoplastic nature of adrenal cortical nodules and underlying germline susceptibilities has also advanced the classification of adrenal cortical nodular disease. For the adrenal medulla, pheochromocytomas (intra‐adrenal paragangliomas) are all regarded as malignant tumours as they all have potential for metastases and are often associated with genetic susceptibilities.

Abstract Introduction/Objective Mutations in KIT and PDGFRA drive the majority of gastrointestinal stromal tumors (GIST) and inform targeted therapy selection. While single-driver mutations are typical, a subset of cases harbors multiple KIT mutations, complicating clinical interpretation. This study investigated the frequency, distribution, and inferred hierarchy of primary and secondary KIT mutations using DNA-based sequencing in a large GIST cohort. Methods/Case Report We retrospectively reviewed 579 GIST cases that underwent DNA-based next-generation sequencing using a custom panel targeting all coding exons of KIT and PDGFRA. Tumor-rich formalin-fixed paraffin-embedded (FFPE) tissue was required. In double-mutant cases, the mutation with higher variant allele frequency (VAF) was presumed to be primary. Results Mutations in KIT or PDGFRA were detected in 482/579 cases (83.2%). Among KIT-mutant cases, 28 had two mutations and one had three. Secondary mutations frequently occurred in exons 13, 14, and 17 and were significantly more common in non-gastric tumors (p &lt; 0.0001). Primary mutations most often involved exon 11. Conclusion VAF analysis enabled classification of mutation hierarchy in cases with multiple KIT mutations. The distinct anatomical and exon-specific distribution of primary vs. secondary mutations highlights their potential therapeutic implications and warrants further study.

Background: Longitudinal genomic profiling through serial circulating tumor DNA (ctDNA) testing offers a noninvasive method to monitor clonal evolution in advanced prostate cancer. This study evaluated the frequency and nature of newly emergent and potentially actionable genomic alterations detected through serial testing in a real-world setting. Methods: We conducted a retrospective analysis of advanced prostate cancer patients who underwent multiple Guardant360 ctDNA tests between October 2020 and March 2023. The study focused on identifying new genomic alterations absent in the initial test, with particular attention to alterations relevant for on-label therapies, therapies approved in other oncologic indications (i.e., off-label), or a clinical trial. Results: Among 479 patients with at least two ctDNA tests, the median interval between the first and second evaluable tests was 207 days. New and potentially actionable alterations emerged in 57.8% of patients, including potential targets for on-label therapies (16.7%), off-label therapies (16.5%), and clinical trials (55.7%). Tumor mutational burden (TMB) increased from “low” to “high” in 11% of patients, although none had microsatellite instability or mismatch repair deficiency. In a Mayo Clinic subset, ten patients received olaparib based on treatment-emergent alterations, but none achieved a prostate-specific antigen (PSA) response. Two patients who transitioned from low to high TMB received pembrolizumab, both with progressive disease as best response. Conclusions: In a large real-world cohort, serial ctDNA testing frequently identified new alterations that were not detected at baseline and are potentially actionable therapeutic targets, highlighting the value of serial genomic profiling for capturing clonal dynamics. Additional research is needed to better establish a framework for retesting and to clarify how these results should influence subsequent treatment decisions.

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).