Citations

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.

Context.— A clinic was created for patients to review their explanted organs with a pathologist. Objective.— To prospectively investigate the benefits of this type of clinic as perceived by both transplant patients and their pathologists. Design.— In this prospective study, patients participated in a videotaped viewing of heart and/or lung explants by the patient and their guest(s) and pathologist (December 2017–August 2022). Patients received a 3D-printed replica of their explant. After viewing the explanted organ, patients and their guests participated in an interview to assess their experiences. Video-reflexive ethnography was used by pathologists for data collection and practice improvement. Results.— Of 143 patients who viewed their explanted organ, 21 patients consented to having the organ-viewing session taped and to participate in a postviewing interview. The study group was comprised of 12 men; the median age was 57.5 years (range, 29–67 years). Five pathologists took part in reflexive sessions. The clinics were viewed positively by patients, providing an opportunity to better understand their disease. Pathologists had a similarly positive experience and gained important insights to patient journeys. Proposals for improvement were brought forward from both patients and pathologists. Conclusions.— Video-reflexive ethnography provided the opportunity for patients and pathologists to reflect on patient-pathology clinic appointments. This work serves as a template to build out pathology-based clinics.

Abstract Recent studies have described the tumor microenvironment and the key transcription factors in untreated small cell lung cancer (SCLC), but less is known about the salient features in recurrent SCLC (rSCLC). This information could provide valuable insight about the effectiveness of second and later line therapies. In this study, we compared transcriptome profiles (by RNA-seq) of rSCLC against untreated primaries (pSCLC). rSCLC samples (n=23) were obtained from frozen biopsies in patients enrolled in our MC1923 (NCT04607954) phase 2 clinical trial whose disease progressed after chemoimmunotherapy. The pSCLC group (n=73) included publicly available data from fresh frozen primary tumors after surgical resections. Normalized expression data were used in immune deconvolution and gene set enrichment analysis (GSEA) in molecular signature database. Additional GSEA included gene sets describing ASCL1 (A), NEUROD1 (N), ASCL1 and NEUROD1 (AN), and POU2F3 (P) transcription factor activities which are used for subtyping of SCLC. Immune deconvolutions by multiple software algorithms suggested depletion of immune infiltrates in rSCLC compared with pSCLC including dendritic cells, B cells, CD8+ T cells, and M1 macrophages. Furthermore, we found decreased chemotaxis and increased apoptosis of dendritic cells, reduced TNF signaling, and reduced lymphocyte co-stimulation in rSCLC by GSEA. Additionally, in comparisons with pSCLC, rSCLC tumors had significantly lower enrichment scores for POU2F3 activity, representing the SCLC-P subtype (p < 0.007). Importantly, the SCLC-P was recently reported to be more immune inflamed than the other A, N, and AN subtypes. Altogether, our analyses provide strong evidence that the tumor microenvironment of rSCLC is significantly more immunosuppressed and with reduced immune cell infiltrates compared to pSCLC. Developing therapeutic strategies aimed at “warming” the tumor microenvironment and enhancing anti-tumor immune activity in ongoing multimodal therapies of recurrent SCLC will likely provide significant benefits to patients. Citation Format: Farhad Kosari, Mohamed Ali, Sarah H. Johnson, Alex Adjei, Julian R. Molina, Aaron S. Mansfield, Anastasios Dimou, Kaushal Parikh, Mohamed Shanshal, Katherine E. Smith, Ailsa G. Luce, Anna J. Schwecke, Janet Lensing, Ying-Chun Lo, John C. Cheville, George Vasmatzis, Konstantinos Leventakos. Small cell lung cancer (SCLC) at recurrence has a “colder” tumor microenvironment than primary SCLC according to gene expression profiling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6614.

ABSTRACT We report a case of a primary cutaneous spindle cell sarcoma (SCS) with FN1 :: FGFR1 fusion. The tumor lacked the typical histologic and immunohistochemical features associated with other FN1 ‐rearranged neoplasms, such as phosphaturic mesenchymal tumors (PMT) and calcified chondroid mesenchymal neoplasms (CCMN). Unlike PMTs, which often feature a cartilaginous matrix and are associated with tumor‐induced osteomalacia (TIO), the present case lacked these characteristics and did not show FGF23 mRNA expression. Immunohistochemically, the tumor cells showed patchy staining for CD34 but were negative for markers such as ERG, desmin, S100, and pan‐TRK. The fusion event in this case involves the loss of the FGFR1 Ig1 (D1) domain, a mechanism proposed to drive oncogenesis by releasing FGFR1 from autoinhibition. Despite the preservation of other FGFR1 domains, no evidence of FGF23 signaling was detected, and the patient had no clinical history of TIO. This case underscores the complexity of oncogenesis in FN1 :: FGFR1 ‐rearranged neoplasms, a form of “promiscuous” gene fusion, where similar fusions lead to diverse tumor phenotypes. It emphasizes the importance of incorporating molecular testing in diagnosing spindle cell sarcomas, particularly those occurring in acral sites, to identify this underrecognized entity.

Abstract Struma ovarii (SO) is a rare subtype of ovarian teratoma composed of more than 50% thyroid tissue. Extraovarian spread of SO, called peritoneal strumosis, was previously considered benign given the lack of histological malignant features. However, the 2020 World Health Organization Classification of Female Genital Tumors reclassified peritoneal strumosis as highly differentiated follicular carcinoma of ovarian origin (HDFCO), highlighting its low-grade malignant potential. We present a 38-year-old woman with SO treated initially with right salpingo-oophorectomy, with recurrence 2 years later with multifocal metastatic lesions in the abdomen and pelvis that was successfully treated with surgical resection, total thyroidectomy, and 157 mCi of I-131. Tumor molecular testing revealed a pathogenic DICER1 variant (c.5428G>T, exon 25). A second variant (c.319delinsTGCTGGTTTGACA, exon 4) was of uncertain significance. Germline testing confirmed the second DICER1 variant and also identified an increased risk variant in the APC gene (c.3920T>A). This is a rare case of extensive HFDCO with DICER1 variants, which has been associated with thyroid cancer. Given the germline DICER1 variant, this may also represent the first reported instance of DICER1 syndrome manifesting as HDFCO. Further research into the prognostic factors and optimal treatment of HFDCO is needed.

Context.— Cardiac and pulmonary allograft recipients represent a unique population, frequently interacting with support groups and exhibiting intense curiosity about their pathology. Like other solid organ transplant patients, they have enduring and frequent interaction with the laboratory for routine allograft surveillance. Objective.— To address patient requests to understand what happens to their explanted organ and to better understand their disease while simultaneously improving awareness of pathologists’ roles in their continuing care. Design.— At routine follow-up appointments, transplant nurse coordinators offer each allograft recipient the opportunity to interact with a pathologist in our “ On My Path ” program. Organ viewing occurs in a private setting, in a specialized room. Relevant pathology is discussed, and questions are answered, with documentation in the medical record. The patient is subsequently gifted a 3-dimensional model of their explanted organ. Transplant coordinators were surveyed for their feedback on the experience. Results.— One hundred fifty-eight interactions have been documented (2017–2022) at our institution, including patients who underwent cardiac transplant (96, 61%), single or bilateral lung transplant (54, 34%), or combination lung and heart transplant (8, 5%). Transplant coordinators reported an increase in patient understanding of their disease and emotional closure related to the disease through the On My Path program. Conclusions.— Pathologists providing direct patient care is a feasible model that addresses currently unmet desires of the transplant population to better understand their pathology. Providing a 3-dimensional model helps to empower patients and drives satisfaction. These interactions also improve awareness about pathology as a discipline and its importance in the continued care of transplant recipients.

Sialadenoma papilliferum (SP) is a rare salivary gland tumor mostly reported in the oral cavity. Here we describe a bronchial SP in the left upper lobe bronchus of a 10-year-old boy. At bronchoscopy, a well-circumscribed polypoid lesion protruding into the bronchial lumen was identified. The tumor was excised, but eventually, the patient had to undergo a sleeve resection after 2 recurrences. Pathology revealed a papillocystic lesion with exophytic and endophytic components. The cells lining the exophytic surface and papillary structures were columnar and squamous, and the cells lining endophytic cystic and papillary structures were cuboidal to columnar, all of which were diffusely reactive with antibodies to SOX10 protein. The presence of basal cells was demonstrated by p63 immunoreactivity. The cells failed to immunohistochemically express BRAF V600E. Fluorescence in situ hybridization analysis revealed no MAML2 or RET gene rearrangement. The patient is alive 24 years after resection with no additional recurrences. Bronchial SP needs to be recognized and distinguished from other benign and malignant salivary gland and pulmonary neoplasms so that patients can receive appropriate treatment and follow-up.

Abstract Accumulating evidence suggests dysregulated immune checkpoint (IC) signaling can exacerbate COVID-19 severity, but the role of these molecules in the pathogenesis of fatal COVID-19-related diffuse alveolar damage (DAD) remains elusive. Understanding how IC proteins influence acute lung injury due to COVID-19 can provide insights into potential therapeutic strategies to modulate immune responses and improve patient outcomes. Here, in a single-center autopsy cohort, we determined the cellular localization of ICs in lung tissue from cases of fatal COVID-19, DAD-comparators, and non-fibrotic controls by using immunohistochemistry, and investigated their association with clinical outcomes. We expanded our findings by performing analyses of publicly available single-cell RNA sequencing datasets from patients with fatal COVID-19 and non-fibrotic controls. We demonstrated the presence of protein-protein interaction networks of ICs in the lung cellular niche by performing transcriptomic profiling of lung tissue-derived RNA counts from patients with fatal COVID-19. Further, we leveraged data from the largest international, multi-center COVID-19 autopsy cohort and validated that, among patients with fatal COVID-19, those with higher PD-L1/CD274 expression in lung endothelial cells had more rapid clinical deterioration. Lastly, in a cohort of individuals with early COVID-19, IC plasma protein levels were elevated in those with persistent SARS-CoV-2 RNAemia and adverse clinical outcomes. Collectively, our data provide unique pathological insights into the role of IC dysregulation and differential disease severity in COVID-19.