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During routine dermatologic examination, a 77-year-old male was noted to have a firm blue subcutaneous nodule on his right lateral upper back. His past medical history included metastatic melanoma of unknown primary involving right and left axillary lymph nodes, treated with ipilimumab/nivolumab with complete response, and subsequent primary uveal melanoma. The subcutaneous nodule was located near his previous right axillary scar for metastatic melanoma. Excision of the nodule showed a plexiform neoplasm involving mid and deep dermis composed of spindle and epithelioid atypical cells admixed with numerous melanophages. Central necrosis was present. Immunohistochemical studies revealed the tumor cells to be diffusely positive for HMB45, with retained expression of BAP1 and p16. The tumor cells were negative for PRAME, nuclear expression of β-catenin, LEF1, and BRAF V600E. Molecular studies demonstrated BAP1 and GNA11 somatic mutations, a profile different from that exhibited by his prior melanoma. Collectively, these data were interpreted as a metastasis from uveal melanoma and not a recurrence of his metastatic likely cutaneous melanoma after complete response to immunotherapy. This case emphasizes the importance of molecular studies for definitive diagnosis in challenging clinical situations, especially when there is discordance among histopathological, immunohistochemical, and molecular studies. Integration of clinical, histopathological, and molecular features is warranted., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Melanoma metabolism can be reprogrammed by activating BRAF mutations. These mutations are present in up to 50% of cutaneous melanomas, with the most common being V600E. BRAF mutations augment glycolysis to promote macromolecular synthesis and proliferation. Prior to the development of targeted anti-BRAF therapies, these mutations were associated with accelerated clinical disease in the metastatic setting. Combination BRAF and MEK inhibition is a first line treatment option for locally advanced or metastatic melanoma harboring targetable BRAF mutations. This therapy shows excellent response rates but these responses are not durable, with almost all patients developing resistance. When BRAF mutated melanoma cells are inhibited with targeted therapies the metabolism of those cells also changes. These cells rely less on glycolysis for energy production, and instead shift to a mitochondrial phenotype with upregulated TCA cycle activity and oxidative phosphorylation. An increased dependence on glutamine utilization is exhibited to support TCA cycle substrates in this metabolic rewiring of BRAF mutated melanoma. Herein we describe the relevant core metabolic pathways modulated by BRAF inhibition. These adaptive pathways represent vulnerabilities that could be targeted to overcome resistance to BRAF inhibitors. This review evaluates current and future therapeutic strategies that target metabolic reprogramming in melanoma cells, particularly in response to BRAF inhibition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To study mechanisms driving/inhibiting skin carcinogenesis, stage-specific expression of 14-3-3σ (Stratifin) was analyzed in skin carcinogenesis driven by activated ras Ha /fos expression (HK1.ras/fos) and ablation of PTEN-mediated AKT regulation (K14.creP/Δ5PTEN flx/flx ). Consistent with 14-3-3σ roles in epidermal differentiation, HK1.ras hyperplasia and papillomas displayed elevated 14-3-3σ expression in supra-basal keratinocytes, paralleled by supra-basal p-MDM2 166 activation and sporadic p-AKT 473 expression. In bi-genic HK1.fos/Δ5PTEN flx/flx hyperplasia, basal-layer 14-3-3σ expression appeared, and alongside p53/p21, was associated with keratinocyte differentiation and keratoacanthoma etiology. Tri-genic HK1.ras/fos-Δ5PTEN flx/flx hyperplasia/papillomas initially displayed increased basal-layer 14-3-3σ, suggesting attempts to maintain supra-basal p-MDM2 166 and protect basal-layer p53. However, HK1.ras/fos-Δ5PTEN flx/flx papillomas exhibited increasing basal-layer p-MDM2 166 activation that reduced p53, which coincided with malignant conversion. Despite p53 loss, 14-3-3σ expression persisted in well-differentiated squamous cell carcinomas (wdSCCs) and alongside elevated p21, limited malignant progression via inhibiting p-AKT1 473 expression; until 14-3-3σ/p21 loss facilitated progression to aggressive SCC exhibiting uniform p-AKT1 473 . Analysis of TPA-promoted HK1.ras-Δ5PTEN flx/flx mouse skin, demonstrated early loss of 14-3-3σ/p53/p21 in hyperplasia and papillomas, with increased p-MDM2 166 /p-AKT1 473 that resulted in rapid malignant conversion and progression to poorly differentiated SCC. In 2D/3D cultures, membranous 14-3-3σ expression observed in normal HaCaT and SP1 ras61 papilloma keratinocytes was unexpectedly detected in malignant T52 ras61/v-fos SCC cells cultured in monolayers, but not invasive 3D-cells. Collectively, these data suggest 14-3-3σ/Stratifin exerts suppressive roles in papillomatogenesis via MDM2/p53-dependent mechanisms; while persistent p53-independent expression in early wdSCC may involve p21-mediated AKT1 inhibition to limit malignant progression., (© 2024 The Author(s). Molecular Carcinogenesis published by Wiley Periodicals LLC.)

Background: Genotype-phenotype associations in recessive dystrophic epidermolysis bullosa (RDEB) have been difficult to elucidate., Objective: To investigate RDEB genotype-phenotype associations and explore a functional approach to genotype classification., Methods: Clinical examination and genetic testing of RDEB subjects, including assessment of clinical disease by RDEB subtype and extent of blistering. Genotypes were evaluated according to each variant's effect on type VII collagen function per updated literature and subsequently categorized by degree of impact on VII collagen function as low-impact (splice/missense, missense/missense), medium-impact (premature termination codon [PTC]/missense, splice/splice), and high-impact (PTC/PTC, PTC/splice). Genotype-phenotype associations were investigated using Kruskal-Wallis and Fisher's exact tests, and age-adjusted regressions., Results: Eighty-three participants were included. High-impact variants were associated with worse RDEB subtype and clinical disease, including increased prevalence of generalized blistering (55.6% for low-impact vs 72.7% medium-impact vs 90.4% high-impact variants, P = .002). In age-adjusted regressions, participants with high-impact variants had 40.8-fold greater odds of squamous cell carcinoma compared to low-impact variants (P = .02), and 5.7-fold greater odds of death compared to medium-impact variants (P = .05)., Limitations: Cross-sectional design., Conclusion: Functional genotype categories may stratify RDEB severity; high-impact variants correlated with worse clinical outcomes. Further validation in larger cohorts is needed., Competing Interests: Conflicts of interest Drs Tang and Marinkovich are investigators for clinical trials sponsored by Abeona Therapeutics, Inc, and Phoenix Tissue Repair. Dr Marinkovich is also an investigator for clinical trials sponsored by WINGS, Castle Creek Pharmaceuticals, and Krystal Biotech. Dr Gorell is a consultant for Krystal Biotech. Dr So, Dr Nazaroff, Dr Yenamandra, Author Harris, Dr Fulchand, Dr Eid, and Author Dolorito have no conflicts of interest to declare., (Copyright © 2024. Published by Elsevier Inc.)

Background: Melanomas lacking mutations in BRAF, NRAS and NF1 are frequently referred to as "triple wild-type" (tWT) melanomas. They constitute 5-10 % of all melanomas and remain poorly characterized regarding clinical characteristics and response to therapy. This study investigates the largest multicenter collection of tWT-melanomas to date., Methods: Targeted next-generation sequencing of the TERT promoter and 29 melanoma-associated genes were performed on 3109 melanoma tissue samples of the prospective multicenter study ADOREG/TRIM of the DeCOG revealing 292 patients suffering from tWT-melanomas. Clinical characteristics and mutational patterns were analyzed. As subgroup analysis, we analyzed 141 tWT-melanoma patients receiving either anti-CTLA4 plus anti-PD1 or anti PD1 monotherapy as first line therapy in AJCC stage IV., Results: 184 patients with cutaneous melanomas, 56 patients with mucosal melanomas, 34 patients with acral melanomas and 18 patients with melanomas of unknown origin (MUP) were included. A TERT promoter mutation could be identified in 33.2 % of all melanomas and 70.5 % of all tWT-melanomas harbored less than three mutations per sample. For the 141 patients with stage IV disease, mPFS independent of melanoma type was 6.2 months (95 % CI: 4-9) and mOS was 24.8 months (95 % CI: 14.2-53.4) after first line anti-CTLA4 plus anti-PD1 therapy. After first-line anti-PD1 monotherapy, mPFS was 4 months (95 %CI: 2.9-8.5) and mOS was 29.18 months (95 % CI: 17.5-46.2)., Conclusions: While known prognostic factors such as TERT promoter mutations and TMB were equally distributed among patients who received either anti-CTLA4 plus anti-PD1 combination therapy or anti-PD1 monotherapy as first line therapy, we did not find a prolonged mPFS or mOS in either of those. For both therapy concepts, mPFS and mOS were considerably shorter than reported for melanomas with known oncogene mutations., Competing Interests: Declaration of Competing Interest All other authors declare no conflicts of interest for the submitted work., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Melanoma poses a poor prognosis with high mortality rates upon metastasis. Exploring the molecular mechanisms governing melanoma progression paves the way for developing novel approaches to control melanoma metastasis and ultimately enhance patient survival rates. Extracellular galectin-3 (Gal-3) has emerged as a pleiotropic promoter of melanoma metastasis, exerting varying activities depending on its interacting partner. However, whether intracellular Gal-3 promotes melanoma aggressive behavior remains unknown. In this study, we explored Gal-3 expression in human melanoma tissues as well as in murine melanoma models to examine its causal role in metastatic behavior. We found that Gal-3 expression is downregulated in metastatic melanoma tissues compared with its levels in primary melanomas. Enforced silencing of Gal-3 in melanoma cells promoted migration, invasion, colony formation, in vivo xenograft growth, and metastasis and activated canonical oncogenic signaling pathways. Moreover, loss of Gal-3 in melanoma cells resulted in upregulated the expression of the prometastatic transcription factor NFAT1 and its downstream metastasis-associated proteins, matrix metalloproteinase 3, and IL-8. Overall, our findings implicate melanoma intracellular Gal-3 as a major determinant of its metastatic behavior and reveal a negative regulatory role for Gal-3 on the expression of NFAT1 in melanoma cells., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The barrier function of skin epidermis is crucial for our bodies to interface with the environment. Because epidermis continuously turns over throughout the lifetime, this barrier must be actively maintained by regeneration. Although several transcription factors have been established as essential activators in epidermal differentiation, it is unclear whether additional factors remain to be identified. In this study, we show that CASZ1, a multi zinc-finger transcription factor previously characterized in nonepithelial cell types, shows highest expression in skin epidermis. CASZ1 expression is upregulated during epidermal terminal differentiation. In addition, CASZ1 expression is impaired in several skin disorders with impaired barrier function, such as atopic dermatitis, psoriasis, and squamous cell carcinoma. Using transcriptome profiling coupled with RNA interference, we identified 674 differentially expressed genes with CASZ1 knockdown. Downregulated genes account for 91.2% of these differentially expressed genes and were enriched for barrier function. In organotypic epidermal regeneration, CASZ1 knockdown promoted proliferation and strongly impaired multiple terminal differentiation markers. Mechanistically, we found that CASZ1 upregulation in differentiation requires the action of both the master transcription factor, p63, and the histone acetyltransferase, p300. Taken together, our findings identify CASZ1 as an essential activator of epidermal differentiation, paving the way for future studies understanding of CASZ1 roles in skin disease., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Cutaneous squamous cell carcinoma (CSCC) is the most deadly disease among nonmelanoma skin cancers. LINC00641 plays a role in various cancers, but its role in CSCC has not been reported so far. Methods and Materials: The expression of LINC00641 and miR-424 in cells was detected by RT-qPCR. CCK-8 and colony formation assay were used to detect the proliferation of cells. Western blot was used to detect the expression levels of proliferation-, invasion-, and migration-related proteins. Wound Healing and Transwell experiments detected the ability of cell invasion and migration. In animal experiments, a tumor-bearing model was established in nude mice, and tumor volume was measured and photographed. The expression levels of proliferation-, invasion-, and migration-related proteins were detected by Western blot. Results: The expression of LINC00641 was significantly decreased in CSCC cell lines. The overexpression of LINC00641 at the cellular level inhibited the proliferation and migration of CSCC cell line A431 by downregulating the expression of miR-424. The overexpression of LINC00641 in animals inhibited the tumor volume of nude mice by downregulating the expression of miR-424 to inhibit the expression of proliferation- and migration-related proteins. Conclusion: LINC00641 inhibits the development of CSCC by downregulating miR-424.

Merkel cell carcinoma (MCC) is a rare, highly aggressive skin cancer of neuroendocrine origin that is typically associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet (UV) light. We report a case of relapsed MCC that presented with new symptoms of fatigue, back pain, and myeloid left shift identified during scheduled follow-up. The patient was found to have circulating neoplastic cells in the peripheral blood and bone marrow metastasis. Immunohistochemistry for synaptophysin, CD56, INSM-1, CK20, CD117 were positive, whereas CD34, TdT, Chromogranin, CD10, myeloperoxidase, CD3 and CD19 were negative. Flow cytometry of the peripheral blood confirmed the presence of an abnormal nonhematopoietic cell population expressing CD56 positivity. A next-generation sequencing (NGS) panel revealed the presence of variants in RB1, TP53, and other genes, some of which have not been previously described in MCC. This rare presentation highlights the challenges in the diagnosis and management of MCC., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Melanoma pathogenesis, conventionally perceived as a linear accumulation of molecular changes, discloses substantial heterogeneity driven by non-linear biological processes, including the direct transformation of melanocyte stem cells. This heterogeneity manifests in diverse biological phenotypes and developmental states, influencing variable responses to treatments. Unveiling the aberrant mechanisms steering melanoma initiation, progression, and metastasis is imperative. Beyond mutations in oncogenic and tumor suppressor genes, the involvement of distinct molecular pathways assumes a pivotal role in melanoma pathogenesis. Ultraviolet (UV) radiations, a principal factor in melanoma etiology, categorizes melanomas based on cumulative sun damage (CSD). The genomic landscape of lesions correlates with UV exposure, impacting mutational load and spectrum of mutations. The World Health Organization's 2018 classification underscores the interplay between sun exposure and genomic characteristics, distinguishing melanomas associated with CSD from those unrelated to CSD. The classification elucidates molecular features such as tumor mutational burden and copy number alterations associated with different melanoma subtypes. The significance of the mutated BRAF gene and its pathway, notably BRAFV600 variants, in melanoma is paramount. BRAF mutations, prevalent across diverse cancer types, present therapeutic avenues, with clinical trials validating the efficacy of targeted therapies and immunotherapy. Additional driver mutations in oncogenes further characterize specific melanoma pathways, impacting tumor behavior. While histopathological examination remains pivotal, challenges persist in molecularly classifying melanocytic tumors. In this review, we went through all molecular characterization that aid in discriminating common and ambiguous lesions. Integration of highly sensitive molecular diagnostic tests into the diagnostic workflow becomes indispensable, particularly in instances where histology alone fails to achieve a conclusive diagnosis. A diagnostic algorithm based on different molecular features inferred by the various studies is here proposed., Competing Interests: Declaration of Competing Interest Authors declare no potential conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Cutaneous neurofibromas (CNFs) are benign tumors that occur in the dermis of individuals with the inherited tumor predisposition disorder, neurofibromatosis type 1. CNFs cause disfigurement, pain, burning, and itching, resulting in substantially reduced QOL in patients with neurofibromatosis type 1. CNFs are benign tumors that exhibit cellular and molecular heterogeneity, making it difficult to develop tractable in vitro or in vivo models. As a result, CNF research and drug discovery efforts have been limited. To address this need, we developed a reproducible patient-derived explant (PDE) ex vivo culture model using CNF tumors from patients with neurofibromatosis type 1. CNF PDEs remain viable in culture for over 9 days and recapitulate the cellular composition and molecular signaling of CNFs. Using CNF PDEs as a model system, we found that proliferation was associated with increased T-cell infiltration. Furthermore, we identified a pattern of reciprocal inflammatory signaling in CNF PDEs in which tumors rely on prostaglandin or leukotriene-mediated signaling pathways. As proof of principle, we show that ex vivo glucocorticoid treatment reduced the expression of proinflammatory genes, confirming that CNF PDEs are a useful model for both mechanistic studies and preclinical drug testing., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Acral lentiginous melanoma (ALM) is the most common subtype of acral melanoma. Even though recent genetic studies are reported in acral melanomas, the genetic differences between in-situ and invasive ALM remain unclear. We aimed to analyze specific genetic changes in ALM and compare genetic differences between in-situ and invasive lesions to identify genetic changes associated with the pathogenesis and progression of ALM. We performed whole genome sequencing of 71 tissue samples from 29 patients with ALM. Comparative analyses were performed, pairing in-situ ALMs with normal tissues and, furthermore, invasive ALMs with normal and in-situ tissues. Among 21 patients with in-situ ALMs, 3 patients (14.3%) had SMIM14 , SLC9B1 , FRG1 , FAM205A , ESRRA , and ESPN mutations, and copy number (CN) gains were identified in only 2 patients (9.5%). Comparing 13 invasive ALMs with in-situ tissues, CN gains were identified in GAB2 in 8 patients (61.5%), PAK1 in 6 patients (46.2%), and UCP2 and CCND1 in 5 patients (38.5%). Structural variants were frequent in in-situ and invasive ALM lesions. Both in-situ and invasive ALMs had very low frequencies of common driver mutations. Structural variants were common in both in-situ and invasive ALMs. Invasive ALMs had markedly increased CN gains, such as GAB2 , PAK1 , UCP2 , and CCND1 , compared with in-situ lesions. These results suggest that they are associated with melanoma invasion., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

In patients with resected non-metastatic melanoma, the liquid biopsy for the assessment of molecular residual disease (MRD) by circulating tumour DNA (ctDNA) represents a promising tool to stratify the risk and to monitor tumour evolution. However, its validation requires the demonstration of analytical validity, clinical validity and utility. Indeed, the development of sensitive and specific assays can optimize prognostication and eventually help clinicians to modulate adjuvant treatments, in order to improve clinical outcomes. Data about ctDNA-guided prognosis stratification is emerging, but clinical trials assessing ctDNA-guided therapeutic decisions are still ongoing. This review aims to depict the role of ctDNA-based MRD assessment in patients with non-metastatic melanoma and to provide a roadmap to face challenges for its introduction into clinical practice., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: PQ reports consulting fees and honoraria from Bristol Myers Squibb, Merck, Merck Sharp & Dohme, Novartis, Pierre Fabre, Roche, Sanofi, and Sun Pharma, and travel, accommodations, or other expenses from Merck Sharp & Dohme and Sanofi; FS received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Novartis, MSD, BMS, Pierre Fabre, Merck, Sanofi, Sun Pharma, IGEA, Philogen, and received consulting fees from Novartis, MSD, Sun Pharma, Pierre Fabre, Philogen; AO has been principal investigator in clinical trials sponsored by AbbVie, Alfasigma, Almirall, Amgen, Difa Cooper, Celgene, Eli-Lilly, Galderma, Janssen, Laboratori Farmacologici Milanesi, Leo Pharma, Novartis, Pfizer, Pierre Fabre, Regeneron, Sanofi, UCB-Pharma, and Boehringer-Ingelheim. All other authors have no potential conflict of interest to disclose., (Copyright © 2024. Published by Elsevier Ltd.)

Laser capture microdissection (LCM) of formalin-fixed, paraffin-embedded sections is a way to analyze gene expression of morphologically distinct areas of tissue, as microscopically visualized with stained tissue sections. Herein, I describe a method for laser dissecting lymphoid aggregates in canine cutaneous and subcutaneous sarcomas and their adjacent sarcoma tissue to determine the differential expression of RNA as determined by NanoString ® nCounter technology. Canine soft tissue sarcomas (STS) are diversely derived mesenchymal neoplasms that, regardless of exact histogenesis, behave similarly and thus have been grouped together as a diagnostic entity. The risk of recurrence and/or metastasis depends on the extent of surgical excision and histologic grade. Lymphoid aggregates are described in these tumors but have not been characterized. In humans, lymphoid aggregates characterized as tertiary lymphoid structures (TLS) improve the prognosis of several tumors, including sarcomas. We sought to determine if RNA expressed by lymphoid aggregates in canine sarcomas was compatible with TLS RNA expression. This chapter describes tissue preparation, staining, laser capture microdissection, and RNA isolation in preparation for digital RNA counting., (© 2025. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The histological similarities between pleomorphic adenomas (PAs) and cutaneous mixed tumors (CMTs) found in certain facial regions can create a diagnostic challenge. Molecular findings reveal common genetic profiles, particularly PLAG1 rearrangements in both PA and CMT. Although molecular distinctions have received limited attention, our observations indicate multiple cases of CMTs carrying the TRPS1::PLAG1 fusion. This clinical experience has driven our investigation into the potential diagnostic utility of TRPS1::PLAG1 fusions for determining tumor origin. Two cohorts consisting of 46 cases of CMT and 45 cases of PA of the salivary glands were obtained from French institutions and reviewed by specialists in each subspecialty. RNA sequencing analysis was conducted to identify the molecular features of cases harboring PLAG1. Clinical, pathological, and molecular data were collected. In this study, cases of CMT exhibited recurrent gene fusions, primarily TRPS1::PLAG1 (74%). These tumors shared characteristic histological features, including tubuloductal differentiation in 55% of cases and squamous metaplasia in varying proportions. In contrast, cases of PA had gene fusions involving PLAG1 with various gene partners, with only one case in which TRPS1::PLAG1 was identified. This disparity was also observed at the transcriptomic level between TRPS1::PLAG1 CMTs and other tumors. However, TRPS1 immunostaining did not correlate with TRPS1::PLAG1 fusion. In conclusion, we report that recurrent TRPS1::PLAG1 fusion CMTs exhibit similar characteristic histological features, including tubuloductal differentiation that is associated with squamous metaplasia in around half of cases. Detection of this fusion could be valuable in correctly identifying the origin of these tumors. © 2024 The Pathological Society of Great Britain and Ireland., (© 2024 The Pathological Society of Great Britain and Ireland.)

Abstract: Primary cutaneous gamma delta T-cell lymphoma (PCGDTCL) is a rare type of non-Hodgkin lymphoma accounting for <1% of primary cutaneous T-cell lymphomas. The exact cause of PCGDTCL is not known, however, it is thought that chronic antigen exposure in the skin may lead to immune dysregulation at the site, resulting in abnormal proliferation of mature, post-thymic cytotoxic gamma delta T cells. Mutations are the most common genetic alteration seen in PCGDTCL, while structural abnormalities such as gene fusions are not common. We report a case of PCGDTCL with atypical immunophenotypic features, including expression of CD5 with lack of cytotoxic marker expression, and a structural alteration leading to FYN deletion at exon 8. Recently, it was described that a deletion of the area between FYN exon 8 and TRAF3IP2 intron 2 results in a novel FYN::TRAF3IP2 fusion in peripheral T-cell lymphoma, not otherwise specified. We describe our patient's clinical course, differential diagnosis, and potential implications of FYN deletion on disease pathogenesis. To our knowledge, this is the first report of an FYN structural alteration to be described in PCGDTCL., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: In contrast to early-onset dysplastic nevi, late-onset atypical nevi of the elderly are more often precursors to distinctive nevoid melanomas. PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry was applied to delineate the nevoid aspect of late-onset oncogenic nevoid pathway. Inducible Skin-Associated Lymphoid Tissue, regulatory T-cell mesenchymal hubs, has emerged as a translational tool and was used to define nevoid oncogenesis within a dynamic meta-analytic pathway., Methods: PRAME immunohistochemistry was applied after designating a histopathologic diagnosis. Late-onset atypical nested lentiginous nevus, lentiginous nested melanoma, and hypercellular nested nevoid melanoma were the diagnostic categories. A positive PRAME for melanoma was set at 75% percentage labeling.A wide-ranging published evidence-based database was incorporated to develop a meta-analytic framework for oncogenic nevogenesis. This combined inducible Skin-Associated Lymphoid Tissue incorporating the pleiotropic functions of regulatory T cells regulating immunity and gene regulatory epigenetics as principal modulators., Results: Concordant-negative PRAME expression was present in 64 of 81 (79%) atypical nested lentiginous nevi, concordant-positive PRAME expression occurred in 54 of 75 (72%) nevoid lentiginous and nested melanomas, and 18 of 23 (78%) nevoid hypercellular nested melanomas., Conclusions: PRAME expression confirmed the existence of a late-onset oncogenic nevoid pathway that can be defined by histopathology. Subsequent meta-analysis data linked to the meta-analytic framework revealed that PRAME is an epigenetic surrogate antigen expressed because of repression of retinoic acid receptor signaling, preventing ligand-induced retinoic acid cellular differentiation, growth arrest, and apoptosis, and promoting melanoma growth and survival for melanomas. PRAME is only a single antigen within a highly complex dynamic framework that governs nevoid oncogenesis. Significantly, the retinoic acid/retinoic acid receptor complex has been shown to modulate the immunosuppressive arm of regulatory T cells underpinning immune tolerance and is pertinent to the broad framework but is not linked to PRAME expression in this arm., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Abstract: The standard treatment of choice for pleomorphic dermal sarcoma (PDS), a relatively uncommon soft tissue sarcoma and 1 morphologically similar to atypical fibroxanthoma, is wide local excision with close clinical follow-up. Studies regarding management of advanced/metastatic PDS with immune checkpoint inhibitors are limited as most STSs have historically been viewed as being immunologically inert. Contradicting this belief, in this report, we describe 2 cases of PDS with a robust host response. Histopathology of both cases revealed a dermal neoplasm comprising mitotically active, pleomorphic, spindled-to-ovoid cells, which were immunohistochemically negative for keratinocytic, melanocytic, and smooth muscle markers. An unusual feature in both cases was the presence of a brisk host response. Additional workup of the infiltrating lymphocyte population revealed an abnormal CD4:CD8 ratio in both cases, with the proportion of CD8 + lymphocytes surpassing (case 1) and equaling (case 2) that of the CD4 + T-lymphocyte population. The increased proportion of CD8 + lymphocytes prompted the additional workup of TCR gene rearrangement, which revealed a clonal population of T lymphocytes in both cases. The robust and clonal T-lymphocyte host response in both of our cases suggests that PDS appears to fit the classic model of an inflammatory-type tumor and may be a candidate for checkpoint inhibition. Future work includes additional reports of cases of PDS with an infiltrating clonal T-lymphocyte population and detailing the function and specificity of the infiltrating T lymphocytes to ascertain whether they have the potential to recognize and lyse the tumors they colonize., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Cutaneous malignant melanoma is the most aggressive and the deadliest form of skin cancer. There are two types of limitations which universally exist in current melanoma therapy: Adverse effects and reduced efficiency. Cytoglobin (CYGB), an iron hexacoordinated globin, is highly enriched in melanocytes and frequently epigenetically silenced during melanoma genesis. The present study aimed to explore its potential role as a biomarker for ferroptosis treatment. It was observed that B16F10 and A375 melanoma cells with loss of CYGB expression were highly sensitive to ferroptosis inducers RSL3 and erastin, whereas G361 melanoma cells with highly enriched CYGB were resistant to RSL3 or erastin. Ectopically overexpressed CYGB rendered B16F10 and A375 cells resistant to RSL3 or erastin, accompanied by decreased proliferation and epithelial‑mesenchymal transition (EMT). By contrast, knockdown of CYGB expression made G361 cells sensitive to ferroptosis induction but induced proliferation and EMT progression of G361 cells. Mechanistically, CYGB‑induced resistance of melanoma cells to ferroptosis may have been associated, in part, with i) Suppression of EMT; ii) upregulation of glutathione peroxidase 4 expression; iii) decrease of labile iron pool. In vivo study also demonstrated that CYGB overexpression rendered xenograft melanoma much more resist to RSL3 treatment. Based on these findings, CYGB is a potential therapeutic biomarker to screen the melanoma patients who are most likely benefit from ferroptosis treatment.

Background: Skin cutaneous melanoma (SKCM) is a highly aggressive and malignant tumor that arises from the malignant transformation of melanocytes. In light of the limitations of existing treatment modalities, there is a pressing need to identify new drug targets for SKCM. Aryl-hydrocarbon receptor nuclear translocator-like (ARNTL), also known as Bmal1, is a gene that has been linked to the onset and progression of cancer. However, its role in SKCM remains understudied., Methods: The expression of Bmal1 mRNA and protein was detected using TCGA, GTEx, CCLE, and ULCAN databases. Moreover, survival analysis was performed to investigate the association between Bmal1 and immune invasion and gene expression in immune infiltrating cells via CIBERSORT, R programming, TIMER, Sangerbox, Kaplan-Meier. The study also explored the role of proteins associated with Bmal1 by using R programming and databases (STRING and GSEA). Both in vitro and in vivo studies were conducted to examine the potential role of Bmal1 in SKCM., Results: Compared to normal tissues, the expression level of Bmal1 was significantly reduced in SKCM. Which has been associated with its poor prognosis. Similarly, its expression in SKCM was substantially correlated with immune infiltration, while biogenic analysis indicated that it could potentially influence the tumor immune microenvironment (TME) by influencing tumor-associated neutrophils (TANs). Moreover, Bmal1 overexpression suppressed the proliferation and invasion of melanoma cells and enhanced apoptosis, migration, and cell colony formation., Conclusion: This study concluded that Bmal1 is a novel biomarker that functions as both a diagnostic and prognostic indicator for the progression of SKCM., Competing Interests: Declaration of competing interest We thank Xue Zhang for her assistance in designed the research and wrote the manuscript. T.L and X.C designed the study and wrote the manuscript. T.L and H.Z performed research and analyzed data, Z.C,W.L and X.W were responsible for the formal analysis and data curation.X.X and B.Z supervised research and wrote the manuscript. All authors read and approved the final manuscript. All authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

In a thorough review of the literature, the complex roles of PRAME (preferentially expressed Antigen of Melanoma) and BAP1 (BRCA1-associated protein 1) have been investigated in uveal melanoma (UM) and cutaneous melanoma. High PRAME expression in UM is associated with poor outcomes and correlated with extraocular extension and chromosome 8q alterations. BAP1 mutations in the UM indicate genomic instability and a poor prognosis. Combining PRAME and BAP1 immunohistochemical staining facilitates effective risk stratification. Mechanistically, both genes are associated with genomic instability, making them promising targets for cancer immunotherapy. Hypomethylation of PRAME, specifically in its promoter regions, is critical for UM progression and contributes to epigenetic reprogramming. Additionally, miR-211 regulation is crucial in melanoma and has therapeutic potential. The way PRAME changes signaling pathways provides clues about the cause of cancer due to genomic instability related to modifications in DNA repair. Inhibition of poly(ADP-ribose) polymerase-1 (PARP-1) and PARP-2 in cells expressing PRAME could lead to potential therapeutic applications. Pathway enrichment analysis underscores the significance of PRAME and BAP1 in melanoma pathogenesis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a transcription factor associated with adaptive responses to cellular stress. Its role in cutaneous squamous cell carcinoma (cSCC) remains poorly understood. The aim of this study was to investigate the role of ARNT in cSCC. Immunohistochemistry revealed downregulation of ARNT in cSCC, precancerous lesions (actinic keratosis), and cells. Knockdown of ARNT in A431 and SCL-1 cells significantly enhanced cell growth and metastasis. Microarray analysis and Ingenuity Pathway Analysis confirmed that loss of ARNT in A431 cells was highly correlated with cell growth and movement and upregulated CXCL3 expression. Cellular and xenograft experiments further confirmed that ARNT regulates cSCC proliferation and invasiveness in a CXCL3-dependent manner. ARNT may regulate CXCL3 expression through ROS-STAT3 pathway. In conclusion, this study demonstrates that ARNT plays a critical role in the development of cSCC and significantly affects the proliferation and metastatic ability of cSCC cells. It has the potential to serve as an ideal treatment target for cSCC., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dake Dong reports financial support was provided by The National Natural Science Foundation of China. Zhanyan Pan reports financial support was provided by The National Natural Science Foundation of China. Dake Dong reports financial support was provided by Wuxi Science and Technology Plan Project. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

N6-methyladenosine (m6A) is the most common and prevalent internal mRNA modification in eukaryotes. m6A modification is a dynamic and reversible process regulated by methyltransferases, demethylases, and m6A binding proteins. Skin cancers, including melanoma and nonmelanoma skin cancers (NMSCs), are among the most commonly diagnosed cancers worldwide. m6A methylation is involved in the regulation of RNA splicing, translation, degradation, stability, translocation, export, and folding. Aberrant m6A modification participates in the pathophysiological processes of skin cancers and is associated with tumor cell proliferation, invasion, migration, and metastasis during cancer progression. In this review, we provide a comprehensive summary of the biological functions of m6A and the most up-to-date evidence related to m6A RNA modification in skin cancer. We also emphasize the potential clinical applications in the diagnosis and treatment of skin cancers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: One of the hereditary syndromes associated with multiple early-onset basal cell carcinomas (BCCs) is basal cell nevus syndrome (BCNS), of which a minority is caused by germline SUFU mutations. Germline SUFU mutations show a spectrum of phenotypes, of which multiple hereditary infundibulocystic basal cell carcinoma syndrome (MHIBCC) is one. Patients with MHIBCC develop multiple basaloid skin tumors from middle age onwards., Methods: Three patients presenting with an MHIBCC phenotype were tested for a germline SUFU mutation. Skin biopsies were assessed by two dermatopathologists., Results: Our study adds three new pathogenic SUFU variants, including a mosaic, to the current literature. Literature suggests a spectrum of phenotypes of patients carrying the same SUFU mutation, which ranges from the MHIBCC phenotype, to BCNS, to patients that develop life-threatening brain tumors. This last risk is significantly higher in germline SUFU mutation carriers when compared to BCNS patients carrying germline PTCH1 mutations., Conclusions: Germline SUFU mutation carriers should be recognized as a distinct group of patients carrying specific health risks, independent of meeting the BCNS criteria. Phenotypic prediction based on the specific SUFU mutation seems unfeasible. It is of utmost importance that the less apparent MHIBCC phenotype is recognized, to provide (second generation) germline SUFU mutation carriers appropriate healthcare., (© 2024 The Author(s). Journal of Cutaneous Pathology published by John Wiley & Sons Ltd.)

Mesenchymal tumors may display morphologic and immunohistochemical overlap with melanocytic tumors, presenting a pitfall for misdiagnosis. We report a 62-year-old woman who presented with a recurrent dermal and subcutaneous tumor over the Achilles tendon 15 years following complete excision. Both the primary and the recurrent tumors were characterized by nests and sheets of epithelioid and spindle cells with eosinophilic cytoplasm and uniform ovoid nuclei. The tumor was positive for S100, SOX10, HMB45, cathepsin K, and p63 (weak), while negative for Melan-A, MiTF, smooth muscle actin, and desmin. Gene fusion analysis of the recurrent tumor revealed a NONO::TFE3 fusion which has been recently reported in two similar cutaneous cases. Our case highlights the potential of a NONO::TFE3 cutaneous epithelioid and spindle cell tumor to recur after a prolonged disease-free interval without evidence of high-grade transformation or distant metastasis. Our findings support its classification as a cutaneous mesenchymal neoplasm of intermediate malignancy., (© 2024 The Author(s). Journal of Cutaneous Pathology published by John Wiley & Sons Ltd.)

Abstract: Comparing studies of molecular ancillary diagnostic tests for difficult-to-diagnose cutaneous melanocytic neoplasms presents a methodological challenge, given the disparate ways accuracy metrics are calculated. A recent report by Boothby-Shoemaker et al investigating the real-world accuracy of the 23-gene expression profile (23-GEP) test highlights this methodological difficulty, reporting lower accuracy than previously observed. However, their calculation method-with indeterminate test results defined as either false positive or false negative-was different than those used in previous studies. We corrected for these differences and recalculated their reported accuracy metrics in the same manner as the previous studies to enable appropriate comparison with previously published reports. This corrected analysis showed a sensitivity of 92.1% (95% confidence interval [CI], 82.1%-100%) and specificity of 94.4% (91.6%-96.9%). We then compared these results directly to previous studies with >25 benign and >25 malignant cases with outcomes and/or concordant histopathological diagnosis by ≥3 dermatopathologists. All studies assessed had enrollment imbalances of benign versus malignant patients (0.8-7.0 ratio), so balanced cohorts were resampled according to the lowest common denominator to calculate point estimates and CIs for accuracy metrics. Overall, we found no statistically significant differences in the ranges of 23-GEP sensitivity, 90.4%-96.3% (95% CI, 80.8%-100%), specificity, 87.3%-96.2% (78.2%-100%), positive predictive value, 88.5%-96.1% (81.5%-100%), or negative predictive value, 91.1%-96.3% (83.6%-100%) between previous studies and the cohort from Boothby-Shoemaker et al with this unified methodological approach. Rigorous standardization of calculation methods is necessary when the goal is direct cross-study comparability., Competing Interests: E. Marks has served as a consultant for Castle Biosciences, Inc. C. J. Cockerell has served as a consultant and advisory board member for Castle Biosciences, Inc. J. H. Rogers, J. J. Siegel, B. H. Russell, and M. S. Goldberg are employees and shareholders of Castle Biosciences, Inc., the current laboratory where the 23-gene expression profile test is performed. The remaining authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

NRAS Q61 mutations are driver genetic alterations associated with common melanocytic nevi. Herein, we describe a case of NRAS-mutant melanocytic tumor with a blue nevus-like morphology. A 71-year-old Japanese man presented with a 4.6-mm nodule on his back. Histopathological examination revealed a dense distribution of spindle-shaped melanocytes in the upper dermis and a sparse distribution of dendritic melanocytes in the mid-dermis. The vertical periadnexal extension reached the deep dermis at the center of the tumor. A small junctional component, hyperpigmentation, sclerotic stroma, mild nuclear atypia, and a few mitotic figures were observed. Immunohistochemical examination revealed no PRAME expression and preserved p16 expression. Diffuse RASQ61R immunoreactivity was observed in these tumor cells. Nuclear β-catenin expression was not observed. Targeted RNA sequencing revealed two mutations, NRAS c.182A>G (Q61R) and FGFR2 c.-157A>G, but no other pathogenic alterations such as BRAF, GNAQ, GNA11, CTNNB1, PRKAR1A, or IDH1 mutations or kinase gene fusions. The histopathology fits that of compound-type blue nevus, which is called "Kamino nevus"; however, this tumor was genetically considered to be on the spectrum of conventional acquired melanocytic nevi but not on that of blue nevi. Morphologically, NRAS-driven melanocytic nevi resemble blue nevi without IDH1 R132C coexistence., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Malignant melanoma (MM) is a highly invasive and therapeutically resistant skin malignancy, posing a significant clinical challenge in its treatment. Programmed cell death plays a crucial role in the occurrence and progression of MM. Sphingolipids (SP), as a class of bioactive lipids, may be associated with many kinds of diseases. SPs regulate various forms of programmed cell death in tumors, including apoptosis, necroptosis, ferroptosis, and more. This review will delve into the mechanisms by which different types of SPs modulate various forms of programmed cell death in MM, such as their regulation of cell membrane permeability and signaling pathways, and how they influence the survival and death fate of MM cells. An in-depth exploration of the role of SPs in programmed cell death in MM aids in unraveling the molecular mechanisms of melanoma development and holds significant importance in developing novel therapeutic strategies., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The most common type of melanoma is cutaneous melanoma (CM). The predominant mutational signature is that of ultraviolet radiation (UVR) exposure. The Cancer Genome Atlas (TCGA) molecular classification includes four major subtypes of CM based on common genetic alterations involving the following genes: BRAF, NRAS, and NF1, with a small fraction being "triple" wild-type. The two main signaling pathway abnormalities in CM are the mitogen-activated protein kinase (MAPK) pathway and the phosphoinositol-3-kinase (PI3K) pathway. Other less common types include mucosal melanomas (MM) and uveal melanoma (UM), which have a significantly different genomic landscape. Although few studies reported rare cases with HPV-positive (HPV+) melanoma, the clinicopathological and molecular characteristic of this entity has not been well-described. Among the 2084 melanoma cases queried at our institution, we identified seven patients diagnosed with HPV+ melanoma (prevalence 0.03 %), including five instances of CM and two of MM. The majority of cases were positive for HPV16 (n = 6). Most of the patients were elderly and with advanced disease (n = 6), although this finding may be attributed to the relative frequency of our institution testing advanced-stage tumors. Histologically, most cases showed high degree of pleomorphism and high mitotic count (5 or more mitoses/mm 2 ) (n = 6). UVR signature was present in the CM, but not in the MM cases. Alterations in either MAPK and/or PI3K pathways were detected in the majority of cases (n = 6). The most common genetic abnormalities detected in this study occurred in the TERT promoter (TERTp) (n = 5), a finding that has been reported to be associated with aggressive disease. Our data shows that while HPV+ melanoma is rare, identifying this disease entity could help guide therapy given the demonstrated genomic alterations., Competing Interests: Declaration of competing interest HG, CO, AE, DAB, MJO, and MGE disclose a financial association with Caris Life Sciences (full-time employment, travel/speaking expenses, stock/stock options)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Advanced-stage cutaneous T-cell lymphomas (CTCLs) are notorious for their highly aggressive behavior, resistance to conventional treatments, and poor prognosis, particularly when large-cell transformation occurs. PEG10 has been recently proposed as a potent driver for large-cell transformation in CTCL. However, the targeting of PEG10 continues to present a formidable clinical challenge that has yet to be addressed. In this study, we report an important post-translational regulatory mechanism of PEG10 in CTCL. USP9X, a deubiquitinase, interacted with and deubiquitinated PEG10, thereby stabilizing PEG10. Knockdown of USP9X or pharmacological targeting of USP9X resulted in a prominent downregulation of PEG10 and its downstream pathway in CTCL. Moreover, USP9X inhibition conferred tumor cell growth disadvantage and enhanced apoptosis in vitro, an effect that occurred in part through its regulation on PEG10. Furthermore, we demonstrated that inhibition of USP9X obviously restrained CTCL tumor growth in vivo and that high expression of USP9X is associated with poor survival in patients with CTCL. Collectively, our findings uncover USP9X as a key post-translational regulator in the stabilization of PEG10 and suggest that targeting PEG10 stabilization through USP9X inhibition may represent a promising therapeutic strategy for advanced-stage CTCL., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: Superficial CD34-positive fibroblastic tumour (SCD34FT) is an uncommon but distinctive low-grade neoplasm of the skin and subcutis that shows frequent CADM3 expression by immunohistochemistry (IHC). In this study, prompted by an index case resembling 'atypical fibrous histiocytoma (FH)' that was positive for CADM3 IHC, we systematically examined a cohort of tumours previously diagnosed as 'atypical FH' by applying CADM3 and fluorescence in situ hybridization (FISH) for PRDM10 rearrangement, to investigate the overlap between these tumour types., Methods and Results: Forty cases of atypical FH were retrieved, including CD34-positive tumours (n = 20) and CD34-negative tumours (n = 20). All tumours were stained for CADM3. All CADM3-positive tumours were evaluated by FISH to assess for PRDM10 rearrangement. Eleven CD34-positive tumours (11/20, 55%) coexpressed CADM3 and were reclassified as SCD34FT. None (0/20) of the CD34-negative atypical FH were CADM3-positive. Reclassified SCD34FT (10/11) arose on the lower extremity, with frequent involvement of the thigh (n = 8). Features suggestive of atypical FH were observed in many reclassified cases including variable cellularity, spindled morphology, infiltrative tumour margins, collagen entrapment, epidermal hyperpigmentation, and acanthosis. Variably prominent multinucleate giant cells, including Touton-like forms, were also present. An informative FISH result was obtained in 10/11 reclassified tumours, with 60% (6/10) demonstrating PRDM10 rearrangement., Conclusion: A significant subset of tumours that histologically resemble atypical FH, and are positive for CD34, coexpress CADM3 and harbour PRDM10 rearrangement, supporting their reclassification as SCD34FT. Awareness of this morphologic overlap and the application of CADM3 IHC can aid the distinction between SCD34FT and atypical FH., (© 2024 John Wiley & Sons Ltd.)

Although miR-199a-5p is linked to the development of numerous cancers, its regulatory role in skin cancer is unclear. In this work, the impact of miR-199a-5p produced by adipose-derived stem cells on malignant melanoma skin cancer was investigated.30 pair tumor tissues and adjacent tissues were obtained from skin cancer patients. Adipose-derived stem cell (ADSCs) were isolated from adipose tissues harvested from healthy subjects. The mRNA relative expression was evaluated via qRT-PCR. Cell proliferation ability was measured via CCK-8 assay. Apoptosis was evaluated via flow cytometry. The connection between miR-199a-5p and SOX4 was confirmed via luciferase reporter assay. Western blot was conducted to evaluate protein expression. MiR-199a-5p was higher expressed in ADSCs exosomes and was lower expressed in skin cancer tissues and cells. ADSCs-derived exosomes inhibited cell invasion of skin cancer. MiR-199a-5p inhibitor enhanced cell viability and invasion. In addition, miR-199a-5p inhibitor suppressed cell apoptosis. MiR-199a-5p NC transfected ADSCs inhibited cell viability and invasion while miR-199a-5p mimic transfected ADSCs further inhibited cell viability and invasion. In addition, miR-199a-5p NC transfected ADSCs enhanced cell apoptosis while miR-199a-5p mimic transfected ADSCs further enhanced cell apoptosis. Luciferase supported the targetscan prediction that miR-199a-5p might control SOX4 expression. SOX4 expression was noticeably lower in the miR-199a-5p mimic group.Exosomes from adipose-derived stem cells inhibited skin cancer progression via miR-199a-5p/SOX4.

MDM4 is upregulated in the majority of melanoma cases and has been described as a "key therapeutic target in cutaneous melanoma". Numerous isoforms of MDM4 exist, with few studies examining their specific expression in human tissues. The changes in splicing of MDM4 during human melanomagenesis are critical to p53 activity and represent potential therapeutic targets. Compounding this, studies relying on short reads lose "connectivity" data, so full transcripts are frequently only inferred from the presence of splice junction reads. To address this problem, long-read nanopore sequencing was utilized to read the entire length of transcripts. Here, MDM4 transcripts, both alternative and canonical, are characterized in a pilot cohort of human melanoma specimens. RT-PCR was first used to identify the presence of novel splice junctions in these specimens. RT-qPCR then quantified the expression of major MDM4 isoforms observed during sequencing. The current study both identifies and quantifies MDM4 isoforms present in melanoma tumor samples. In the current study, we observed high expression levels of MDM4-S, MDM4-FL, MDM4-A, and the previously undescribed Ensembl transcript MDM4-209. A novel transcript lacking both exons 6 and 9 is observed and named MDM4-A/S for its resemblance to both MDM4-A and MDM4-S isoforms.

Introduction: Up to 88% of sentinel lymph node biopsies (SLNBs) are negative. The 31-gene expression profile (31-GEP) test can help identify patients with a low risk of SLN metastasis who can safely forego SLNB. The 31-GEP classifies patients as low (Class 1 A), intermediate (Class 1B/2A), or high risk (Class 2B) for recurrence, metastasis, and SLN positivity. The integrated 31-GEP (i31-GEP) combines the 31-GEP risk score with clinicopathologic features using a neural network algorithm to personalize SLN risk prediction., Methods: Patients from a single surgical center with 31-GEP results were included (n = 156). An i31-GEP risk prediction < 5% was considered low risk of SLN positivity. Chi-square was used to compare SLN positivity rates between groups., Results: Patients considered low risk by the i31-GEP had a 0% (0/30) SLN positivity rate compared to a 31.9% (30/94, p < 0.001) positivity rate in those with > 10% risk. Using the i31-GEP to guide SLNB decisions could have significantly reduced the number of unnecessary SLNBs by 19.2% (30/156, p < 0.001) for all patients and 33.0% (30/91, p < 0.001) for T1-T2 tumors. Patients with T1-T2 tumors and an i31-GEP-predicted SLN positivity risk > 10% had a similar SLN positivity rate (33.3%) as patients with T3-T4 tumors (31.3%)., Conclusion: The i31-GEP identified patients with < 5% risk of SLN positivity who could safely forego SLNB. Combining the 31-GEP with clinicopathologic features for a precise risk estimate can help guide risk-aligned patient care decisions for SLNB to reduce the number of unnecessary SLNBs and increase the SLNB positivity yield if the procedure is performed., (© 2024. The Author(s).)

Melanoma, arising from the malignant transformation of melanocytes, stands as the most lethal type of skin cancer. While significant strides have been made in targeted therapy and immunotherapy, substantially enhancing therapeutic efficacy, the prognosis for melanoma patients remains unoptimistic. SIRT7, a nuclear-localized deacetylase, plays a pivotal role in maintaining cellular homeostasis and adapting to external stressors in melanoma, with its activity closely tied to intracellular nicotinamide adenine dinucleotide (NAD + ). However, its involvement in adaptive resistance to targeted therapy remains unclear. Herein, we unveil that up-regulated SIRT7 promotes mitochondrial biogenesis to render the adaptive resistance to MAPK inhibition in melanoma. Initially, we observed a significant increase of SIRT7 expression in publicly available datasets following targeted therapy within a short duration. In consistent, we found elevated SIRT7 expression in melanoma cells subjected to BRAF or MEK inhibitors in vitro. The up-regulation of SIRT7 expression was also confirmed in xenograft tumors in mice after targeted therapy in vivo. Furthermore, we proved that SIRT7 deficiency led to decreased cell viability upon prolonged exposure to BRAF or MEK inhibitors, accompanied by an increase in cell apoptosis. Mechanistically, SIRT7 deficiency restrained the upregulation of genes associated with mitochondrial biogenesis and intracellular ATP levels in response to targeted therapy treatment in melanoma cells. Ultimately, we proved that SIRT7 deficieny could sensitize BRAF-mutant melanoma cells to MAPK inhibition targeted therapy in vivo. In conclusion, our findings underscore the role of SIRT7 in fostering adaptive resistance to targeted therapy through the facilitation of mitochondrial biogenesis. Targeting SIRT7 emerges as a promising strategy to overcome MAPK inhibitor adaptive resistance in melanoma., Competing Interests: Declaration of competing interest The authors have declared no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Melanoma is the most severe type of skin cancer and among the most malignant neoplasms in humans. With the growing incidence of melanoma, increased numbers of therapeutic options, and the potential to target specific proteins, understanding the basic mechanisms underlying the disease's progression and resistance to treatment has never been more important. LOXL3, SNAI1, and NES are key factors in melanoma genesis, regulating tumor growth, metastasis, and cellular differentiation. In our study, we explored the potential role of LOXL3, SNAI1, and NES in melanoma progression and metastasis among patients with dysplastic nevi, melanoma in situ, and BRAF + and BRAF - metastatic melanoma, using immunofluorescence and qPCR analysis. Our results reveal a significant increase in LOXL3 expression and the highest NES expression in BRAF + melanoma compared to BRAF -, dysplastic nevi, and melanoma in situ. As for SNAI1, the highest expression was observed in the metastatic melanoma group, without significant differences among groups. We found co-expression of LOXL3 and SNAI1 in the perinuclear area of all investigated subgroups and NES and SNAI1 co-expression in melanoma cells. These findings suggest a codependence or collaboration between these markers in melanoma EMT, suggesting new potential therapeutic interventions to block the EMT cascade that could significantly affect survival in many melanoma patients.

Objectives: New diagnostic criteria for NF2-related schwannomatosis (NF2) were published in 2022. An updated UK prevalence was generated in accordance with these, with an emphasis on the rate of de novo NF2 (a 50% frequency is widely quoted in genetic counselling). The distribution of variant types among de novo and familial NF2 cases was also assessed., Methods: The UK National NF2 database identifies patients meeting updated NF2 criteria from a highly ascertained population cared for by England's specialised service. Diagnostic prevalence was assessed on 1 February 2023. Molecular analysis of blood and, where possible, tumour specimens for NF2, LZTR1 and SMARCB1 was performed., Results: 1084 living NF2 patients were identified on prevalence day (equivalent to 1 in 61 332). The proportion with NF2 inherited from an affected parent was only 23% in England. If people without a confirmed molecular diagnosis or bilateral vestibular schwannoma are excluded, the frequency of de novo NF2 remains high (72%). Of the identified de novo cases, almost half were mosaic. The most common variant type was nonsense variants, accounting for 173/697 (24.8%) of people with an established variant, but only 18/235 (7.7%) with an inherited NF2 pathogenic variant (p<0.0001). Missense variants had the highest proportion of familial association (56%). The prevalence of LZTR1 -related schwannomatosis and SMARCB1 -related schwannomatosis was 1 in 527 000 and 1 in 1.1M, respectively, 8.4-18.4 times lower than NF2., Conclusions: This work confirms a much higher rate of de novo NF2 than previously reported and highlights the benefits of maintaining patient databases for accurate counselling., Competing Interests: Competing interests: DGE has received consultancy fees from AstraZeneca, Springworks and Everything Genetic Ltd., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

POT1 is the second most frequently reported gene (after CDKN2A ) in familial melanoma. Pathogenic variants are associated with earlier onset and/or multiple primary melanomas (MPMs). To date, POT1 phenotypical reports have been largely restricted to associated malignancies, and description of the dermatological landscape has been limited. We identified 10 variants in n=18 of 384 (4.7%) unrelated individuals (n=13 MPMs; n=5 single primary melanomas) of European ancestry. Five variants were rare (minor allele frequency <0.001) or novel (two loss-of-function (LOF), one splice acceptor and two missense) and were predicted to be functionally significant, in five unrelated probands with MPMs (≥3 melanomas). We performed three-dimensional total body photography on both individuals with confirmed pathogenic LOF variants to characterise the dermatological phenotype. Total body naevus counts (≥2 mm diameter) were significantly higher (p=7.72 ×10-12 ) in carriers compared with a control population. Majority of naevi were on the probands' back and lower limb regions, where only mild to moderate ultraviolet (UV) damage was observed. Conversely, the head/neck region, where both probands exhibited severe UV damage, had comparably fewer naevi. We hypothesise that carriage of functionally significant POT1 variants is associated with increased naevus counts generally, and naevi >5 mm in diameter specifically and the location of these are independent of UV damage., Competing Interests: Competing interests: PS is a shareholder of MoleMap Limited and e-derm consult and undertakes regular teledermatological reporting for both companies. PS is a medical consultant for Canfield Scientific and Blaze Bioscience MoleMap Australia Limited, and a medical advisor for First Derm. No other authors have conflicts to declare., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Resistance biomarkers are needed to identify patients with advanced melanoma obtaining a response to ICI treatment and developing resistance later. We searched a combination of molecular signatures of response to ICIs in patients with metastatic melanoma. In a retrospective study on patients with metastatic melanoma treated with an anti-PD-1 agent carried out at Istituto Nazionale Tumori-IRCCS-Fondazione "G. Pascale", Naples, Italy. We integrated a whole proteome profiling of metastatic tissue with targeted transcriptomics. To assess the prognosis of patients according to groups of low and high risk, we used PFS and OS as outcomes. To identify the proteins and mRNAs gene signatures associated with the patient's response groups, the discriminant analysis for sparse data performed via partial least squares procedure was performed. Tissue samples from 22 patients were analyzed. A combined protein and gene signature associated with poorer response to ICI immunotherapy in terms of PFS and OS was identified. The PFS and OS Kaplan-Meier curves were significantly better for patients with high expression of the protein signature compared to patients with low expression of the protein signature and who were high-risk (Protein: HR = 0.023, 95% CI: 0.003-0.213; p < 0.0001. Gene: HR = 0.053, 95% CI: 0.011-0.260; p < 0.0001). The Kaplan-Meier curves showed that patients with low-risk gene signatures had better PFS (HR = 0 0.221, 95% CI: 0.071-0.68; p = 0.007) and OS (HR = 0.186, 95% CI: 0.05-0.695; p = 0.005). The proteomic and transcriptomic combined analysis was significantly associated with the outcomes of the anti-PD-1 treatment with a better predictive value compared to a single signature. All the patients with low expression of protein and gene signatures had progression within 6 months of treatment (median PFS = 3 months, 95% CI: 2-3), with a significant difference vs. the low-risk group (median PFS = not reached; p < 0.0001), and significantly poorer survival (OS = 9 months, 95% CI: 5-9) compared to patients with high expression of protein and gene signatures (median OS = not reached; p < 0.0001). We propose a combined proteomic and transcriptomic signature, including genes involved in pro-tumorigenic pathways, thereby identifying patients with reduced probability of response to immunotherapy with ICIs for metastatic melanoma.

An optimum safety excision margin (EM) delineated by precise demarcation of field cancerization along with reliable biomarkers that enable predicting and timely evaluating patients' response to immunotherapy significantly impact effective management of melanoma. In this study, optimized biphasic "immunofluorescence staining integrated with fluorescence insitu hybridization" (iFISH) was conducted along the diagnosis-metastasis-treatment-cellular MRD axis to longitudinally co-detect a full spectrum of intact CD31 - aneuploid tumor cells (TCs), CD31 + aneuploid tumor endothelial cells (TECs), viable and necrotic circulating TCs (CTCs) and circulating TECs (CTECs) expressing PD-L1, Ki67, p16 and Vimentin in unsliced specimens of the resected primary tumor, EM, dissected sentinel lymph nodes (SLNs) and peripheral blood in an early-stage melanoma patient. Numerous PD-L1 + aneuploid TCs and TECs were detected at the conventional safety EM (2 cm), quantitatively indicating the existence of a field cancerized EM for the first time. Contrary to highly heterogeneous PD-L1 expression and degrees of Chr8 aneuploidy in TCs and TECs in the primary lesions as well as CTCs and CTECs in peripheral blood, almost all TCs and TECs in SLNs and EM were homogeneously PD-L1 + haploid cells. Dynamic monitoring and cellular MRD assessment revealed that, in contrast to PD-L1 + CTCs being responsive to the immune checkpoint inhibitor (ICI-anti-PD-1), multiploid (≥pentasomy 8) PD-L1 + and Ki67 + CTECs were respectively resistant to ICI-sensitized T cells. In therapeutically stressed lymphatic and hematogenous metastatic cascades, stratified phenotypic and karyotypic profiling of iFISH tissue and liquid biopsied TCs, TECs, CTCs and CTECs in future large-cohort studies will enable appropriate re-specification of the optimal safety EM and distribution mapping of in-depth characterized, subcategorized target cells to help illustrate their metastatic relevance, ultimately improving risk stratification and clinical intervention of tumor progression, metastases, therapy resistance and cancer relapse., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The large T antigen (LT) of the Merkel cell polyomavirus (MCPyV) is crucial for Merkel cell carcinoma (MCC), a rare but very aggressive form of neuroendocrine skin cancer. The clonal integration of MCPyV DNA into the host genome is a signature event of this malignancy. The resulting expression of oncogenes, including the small T (sT) antigen and a truncated form of the LT (truncLT), directly contribute to carcinogenesis. The truncation of the C-terminus of LT prevents the virus from replicating due to the loss of the origin binding domain (OBD) and the helicase domain. This precludes cytopathic effects that would lead to DNA damage and ultimately cell death. At the same time, the LxCxE motif in the N-terminus is retained, allowing truncLT to bind the retinoblastoma protein (pRb), a cellular tumor suppressor. The continuously inactivated pRb promotes cell proliferation and tumor development. truncLT exerts several classical functions of an oncogene: altering the host cell cycle, suppressing innate immune responses to viral DNA, causing immune escape, and shifting metabolism in favor of cancer cells. Given its central role in MCC, the LT is a major target for therapeutic interventions with novel approaches, such as immune checkpoint inhibition, T cell-based immunotherapy, and cancer vaccines., Competing Interests: The authors declare no conflicts of interest.

Cemiplimab has demonstrated relevant clinical activity in cutaneous squamous cell carcinoma (cSCC) but mechanisms of primary and acquired resistance to immunotherapy are still unknown. We collected clinical data from locally advanced and/or metastatic cSSC patients treated with cemiplimab in two Italian University centers. In addition, gene expression analysis by using Nanostring Technologies platform to evaluate 770 cancer- and immune-related genes on 20 tumor tissue samples (9 responders and 11 non-responders to cemiplimab) was performed. We enrolled 81 patients with a median age of 82 years. After 16.4 months of median follow-up, 12- and 24-months PFS were 53% and 42%, respectively; while 12- and 24-months OS were 71% and 61%, respectively. Treatment was well tolerated. Overall response rate (ORR) was 58%, with a disease control rate (DCR) of 77.8%. The difference between genes expressed in responder versus non-responder patient samples was substantial, particularly for genes involved in immune system regulation. Cemiplimab-resistant tumors were associated with over-expression of CCL-20 and CXCL-8. Cemiplimab confirmed efficacy and safety data in real-life cSCC patients. Overexpression of CCL-20 and CXCL-8 could represent biomarkers of lack of response to immunotherapy., Competing Interests: S.N. had travel grants from Amgen, Merck outside of the submitted works. D.C. had travel support from Sanofi, BMS, Merck serono outside of the submitted works. F.C. was advisory board for Amgen, Servier, MSD, Merck, Roche, Pfizer, Bayer, Pierre Fabre, Eisai outside of the submitted work. T.T. was advisory board for Amgen, MSD, Pierre Fabre, Roche, Merck outside of the submitted work. All remaining authors have no competing interests., (© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome is an autosomal-dominant disorder that results from a germline pathogenic variant in the fumarate hydratase (FH) gene on chromosome 1, characterised by renal cell carcinoma (RCC), cutaneous leiomyoma and uterine leiomyoma. Leiomyosarcomas are reported in less than 1% of those with HLRCC. We report a case of a man in his 30s who had a long-standing plaque excised from the left upper arm after undergoing a radical nephrectomy for a fumarate-deficient RCC, with histological exam revealing a grade 1 leiomyosarcoma. Genetic testing confirmed a heterozygous pathogenic variant in the FH gene. This is a rare case of leiomyosarcoma associated with HLRCC, and our patient remains under surveillance with interval abdominal imaging and skin examination. Leiomyosarcomas are difficult to distinguish clinically from their benign counterpart; therefore, histopathological examination is paramount with a low threshold for excision., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Neoadjuvant therapy improves recurrence-free survival (RFS) in resectable stage III cutaneous melanoma. However, accurately predicting individual recurrence risk remains a significant challenge. We investigated circulating tumour DNA (ctDNA) as a biomarker for recurrence in measurable stage IIIB/C melanoma patients undergoing neoadjuvant immunotherapy., Methods: Plasma samples were collected pre-neoadjuvant treatment, pre-surgery and/or six weeks post-surgery from 40 patients enrolled in the OpACIN-neo and PRADO clinical trials. Patients received two cycles of ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) before surgery. Cell free DNA (cfDNA) underwent unbiased pre-amplification followed by tumour-informed mutation detection using droplet digital polymerase chain reaction (ddPCR) with the Bio-Rad QX600 PCR system., Results: Pre-treatment ctDNA was detectable in 19/40 (48%) patients. Among these, 17/19 (89%) zero-converted within six weeks of surgery and none recurred. Positive ctDNA post-surgery (N = 4), irrespective of pre-treatment ctDNA status, was 100% predictive of recurrence (sensitivity 44%, specificity 100%). Furthermore, ctDNA cleared prior to surgery in 7/9 (78%) patients who did not recur, warranting further investigation into ctDNA-guided surgical management., Conclusion: Post-surgery ctDNA positivity and zero-conversion are highly predictive of recurrence, offering a window for personalised modification of adjuvant therapy., (© 2024. The Author(s).)

Melanoma is a malignant skin tumor with a high mortality rate. Regulatory T cells (Tregs) are immune cells with immunosuppressive roles, however, the precise mechanisms governing Treg involvement in melanoma remain enigmatic. Experimental findings unveiled different transcription factor switches between normal and tumor T cell, with heightened FOXP3 and BATF in the latter. These factors induced immunosuppressive molecules and Treg maintenance genes, polarizing tumor T cells into Tregs. Spatial transcriptomics illuminated the preferential settlement of Tregs at the melanoma periphery. Within this context, FOXP3 in Tregs facilitated direct enhancement of specific ligand gene expression, fostering communication with neighboring cells. Novel functional molecules bound to FOXP3 or BATF in Tregs, such as SPOCK2, SH2D2A, and ligand molecules ITGB2, LTA, CLEC2C, CLEC2D, were discovered, which had not been previously reported in melanoma Treg studies. Furthermore, we validated our findings in a large number of clinical samples and identified the Melanoma Treg-Specific Regulatory Tag Set (Mel TregS). ELISA analysis showed that the protein levels of Mel TregS in melanoma Tregs were higher than in normal Tregs. We then utilized SERS technology to measure the signal values of Mel TregS in exosome, and successfully discriminated between healthy individuals and melanoma patients, as well as early and late-stage patients. This approach significantly enhanced detection sensitivity. In sum, our research elucidated fresh insights into the mechanisms governing Treg self-maintenance and communication with surrounding cells in melanoma. We also introduced an innovative method for clinical disease monitoring through SERS technology., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)