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Merkel cell carcinoma (MCC) is an aggressive skin cancer frequently caused by genomic integration of the Merkel cell polyomavirus (MCPyV). MCPyV‐negative cases often present as combined MCCs, which represent a distinctive subset of tumors characterized by association of an MCC with a second tumor component, mostly squamous cell carcinoma. Up to now, only exceptional cases of combined MCC with neuroblastic differentiation have been reported. Herein we describe two additional combined MCCs with neuroblastic differentiation and provide comprehensive morphologic, immunohistochemical, transcriptomic, genetic and epigenetic characterization of these tumors, which both arose in elderly men and appeared as an isolated inguinal adenopathy. Microscopic examination revealed biphasic tumors combining a poorly differentiated high‐grade carcinoma with a poorly differentiated neuroblastic component lacking signs of proliferation. Immunohistochemical investigation revealed keratin 20 and MCPyV T antigen (TA) in the MCC parts, while neuroblastic differentiation was confirmed in the other component in both cases. A clonal relation of the two components can be deduced from 20 and 14 shared acquired point mutations detected by whole exome analysis in both combined tumors, respectively. Spatial transcriptomics demonstrated a lower expression of stem cell marker genes such as SOX2 and MCM2 in the neuroblastic component. Interestingly, although the neuroblastic part lacked TA expression, the same genomic MCPyV integration and the same large T‐truncating mutations were observed in both tumor parts. Given that neuronal transdifferentiation upon TA repression has been reported for MCC cell lines, the most likely scenario for the two combined MCC/neuroblastic tumors is that neuroblastic transdifferentiation resulted from loss of TA expression in a subset of MCC cells. Indeed, DNA methylation profiling suggests an MCC‐typical cellular origin for the combined MCC/neuroblastomas. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer associated with integration of Merkel cell polyomavirus (MCPyV). MCPyV‐encoded T‐antigens (TAs) are pivotal for sustaining MCC's oncogenic phenotype, i.e., repression of TAs results in reactivation of the RB pathway and subsequent cell cycle arrest. However, the MCC cell line LoKe, characterized by a homozygous loss of the RB1 gene, exhibits uninterrupted cell cycle progression after shRNA‐mediated TA repression. This unique feature allows an in‐depth analysis of the effects of TAs beyond inhibition of the RB pathway, revealing the decrease in expression of stem cell‐related genes upon panTA‐knockdown. Analysis of gene regulatory networks identified members of the E2F family (E2F1, E2F8, TFDP1) as key transcriptional regulators that maintain stem cell properties in TA‐expressing MCC cells. Furthermore, minichromosome maintenance (MCM) genes, which encodes DNA‐binding licensing proteins essential for stem cell maintenance, were suppressed upon panTA‐knockdown. The decline in stemness occurred simultaneously with neural differentiation, marked by the increased expression of neurogenesis‐related genes such as neurexins, BTG2, and MYT1L. This upregulation can be attributed to heightened activity of PBX1 and BPTF, crucial regulators of neurogenesis pathways. The observations in LoKe were confirmed in an additional MCPyV‐positive MCC cell line in which RB1 was silenced before panTA‐knockdown. Moreover, spatially resolved transcriptomics demonstrated reduced TA expression in situ in a part of a MCC tumor characterized by neural differentiation. In summary, TAs are critical for maintaining stemness of MCC cells and suppressing neural differentiation, irrespective of their impact on the RB‐signaling pathway. [ABSTRACT FROM AUTHOR]

Aims: Porocarcinoma is a malignant sweat gland tumour differentiated toward the upper part of the sweat duct and may arise from the transformation of a preexisting benign poroma. In 2019, Sekine et al. demonstrated the presence of YAP1::MAML2 and YAP1::NUTM1 fusions in most poromas and porocarcinomas. Recently, our group identified PAK2‐fusions in a subset of benign poromas. Herein we report a series of 12 porocarcinoma cases harbouring PAK1/2/3 fusions. Methods and Results: Five patients were male and the median age was 79 years (ranges: 59–95). Tumours were located on the trunk (n = 7), on the thigh (n = 3), neck (n = 1), or groin area (n = 1). Four patients developed distant metastases. Microscopically, seven cases harboured a benign poroma component and a malignant invasive part. Ductal formations were observed in all, while infundibular/horn cysts and cells with vacuolated cytoplasm were detected in seven and six tumours, respectively. In three cases, the invasive component consisted of a proliferation of elongated cells, some of which formed pseudovascular spaces, whereas the others harboured a predominant solid or trabecular growth pattern. Immunohistochemical staining for CEA and EMA confirmed the presence of ducts. Focal androgen receptor expression was detected in three specimens. Whole RNA sequencing evidenced LAMTOR1::PAK1 (n = 2), ZDHHC5::PAK1 (n = 2), DLG1::PAK2, CTDSP1::PAK1, CTNND1::PAK1, SSR1::PAK3, CTNNA1::PAK2, RNF13::PAK2, ROBO1::PAK2, and CD47::PAK2. Activating mutation of HRAS (G13V, n = 3, G13R, n = 1, Q61L, n = 2) was present in six cases. Conclusion: Our study suggests that PAK1/2/3 fusions is the oncogenic driver of a subset of porocarcinomas lacking YAP1 rearrangement. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Sebaceous gland carcinomas are rare malignant cutaneous adnexal tumors with sebocytic differentiation. The typical predilection area is the head and neck region, where sebaceous gland carcinomas are the most common malignant adnexal tumors of the skin. According to their localization a distinction is made between periocular and extraocular sebaceous gland carcinomas. Muir‐Torre syndrome (MTS) should always be ruled out if it is suspected. In terms of prognosis, sebaceous gland carcinomas are potentially aggressive tumors with a clear tendency to recur and metastasize. Only small extraocular sebaceous gland carcinomas that have been completely resected have a very good prognosis. Sebaceous gland carcinomas most frequently metastasize lymphogenously to regional or distant lymph nodes; organ metastasis occurs less frequently. Periocular sebaceous gland carcinomas have a higher metastasis rate (up to 15%) than extraocular sebaceous gland carcinomas (up to 2%). Complete micrographically controlled surgery (MCS) of the primary tumor is the therapy of first choice, regardless of periocular or extraocular localization. Adjuvant or therapeutic radiotherapy may be considered. There is currently no established standard therapy for advanced, inoperable, or metastatic sebaceous gland carcinomas. Local procedures and systemic therapies such as chemotherapy or immunotherapy can be considered. The procedure should be determined individually by an interdisciplinary tumor board. Close follow‐up care is recommended for these potentially aggressive carcinomas. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Actinic keratosis (AK) are common lesions in light‐skinned individuals that can potentially progress to cutaneous squamous cell carcinoma (cSCC). Both conditions may be associated with significant morbidity and constitute a major disease burden, especially among the elderly. To establish an evidence‐based framework for clinical decision making, the guideline "actinic keratosis and cutaneous squamous cell carcinoma" was updated and expanded by the topics cutaneous squamous cell carcinoma in situ (Bowen's disease) and actinic cheilitis. The guideline is aimed at dermatologists, general practitioners, ear nose and throat specialists, surgeons, oncologists, radiologists and radiation oncologists in hospitals and office‐based settings, as well as other medical specialties, policy makers and insurance funds involved in the diagnosis and treatment of patients with AK and cSCC. A separate guideline exists for patients and their relatives. In this part, we will address aspects relating to epidemiology and etiology, diagnostics, surgical and systemic treatment of cutaneous squamous cell carcinoma (cSCC), surveillance and prevention. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article discusses a case report of a 75-year-old man with metastatic Merkel cell carcinoma (MCC) that was refractory to anti-PD-1 and anti-PD-L1 monotherapy. The patient showed a durable response to combined immunotherapy with ipilimumab (anti-CTLA-4) plus nivolumab (anti-PD-1). This case is the first to demonstrate a complete response to this combination therapy in a patient who did not respond to PD-L1 and PD-1 monotherapy. The findings suggest that the addition of a CTLA-4 inhibitor may enhance the anti-tumoral immunological response in MCC. [Extracted from the article]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Merkel cell carcinoma (MCC, ICD‐O M8247/3) is a rare, malignant, primary skin tumor with epithelial and neuroendocrine differentiation. The tumor cells share many morphologic, immunohistochemical, and ultrastructural features with cutaneous Merkel cells. Nevertheless, the cell of origin of MCC is unclear. MCC appears clinically as a reddish to purple spherical tumor with a smooth, shiny surface and a soft to turgid, elastic consistency, usually showing rapid growth. Spontaneous and often complete regressions of the tumor are observed. These likely immunologically‐mediated regressions explain the cases in which only lymph node or distant metastases are found at the time of initial diagnosis and why the tumor responds very well to immunomodulatory therapies even at advanced stages. Due to its aggressiveness, the usually given indication for sentinel lymph node biopsy, the indication of adjuvant therapies to be evaluated, as well as the complexity of the necessary diagnostics, clinical management should already be determined by an interdisciplinary tumor board at the time of initial diagnosis. [ABSTRACT FROM AUTHOR]

Zusammenfassung: Das Kaposi‐Sarkom (KS) ist eine seltene, maligne, von lymphatischen Endothelzellen ausgehende, multilokuläre Gefäßerkrankung, die vor allem Haut und Schleimhäute, aber auch das lymphatische System und innere Organe wie den Gastrointestinaltrakt, die Lunge oder die Leber befallen kann. Fünf epidemiologische Subtypen des KS mit variablem klinischem Verlauf und unterschiedlicher Prognose werden unterschieden, die in spezifischen Populationen vermehrt auftreten: (1) klassisches KS, (2) iatrogenes KS bei Immunsuppression, (3) endemisches (afrikanisches) lymphadenopathisches KS, (4) epidemisches, HIV‐assoziiertes KS und mit einem Immunrekonstitutions‐Inflammations‐Syndrom (IRIS) assoziiertes KS und (5) KS bei Männern, die Sex mit Männern haben (MSM) ohne HIV‐Infektion. Diese interdisziplinäre Leitlinie fasst aktuelle praxisrelevante Empfehlungen zu Diagnostik und Therapie der verschiedenen Formen des KS zusammen. Die in dieser Kurzleitlinie genannten Empfehlungen werden in der Langfassung der Leitlinie (Online‐Version des JDDG) detaillierter ausgeführt. [ABSTRACT FROM AUTHOR]

Summary: Kaposi's sarcoma (KS) is a rare, malignant, multilocular vascular disease originating from lymphatic endothelial cells that can primarily affect the skin and mucous membranes, but also the lymphatic system and internal organs such as the gastrointestinal tract, lungs or liver. Five epidemiological subtypes of KS with variable clinical course and prognosis are distinguished, with increased incidence in specific populations: (1) Classical KS, (2) Iatrogenic KS in immunosuppression, (3) Endemic (African) lymphadenopathic KS, (4) Epidemic, HIV‐associated KS and KS associated with immune reconstitution inflammatory syndrome (IRIS), and (5) KS in men who have sex with men (MSM) without HIV infection. This interdisciplinary guideline summarizes current practice‐relevant recommendations on diangostics and therapy of the different forms of KS. The recommendations mentioned in this short guideline are elaborated in more detail in the extended version of the guideline (online format of the JDDG). [ABSTRACT FROM AUTHOR]

Detailed examination of tumor components is leading‐edge to establish personalized cancer therapy. Accompanying research on cell‐free DNA, the cell count of circulating tumor cells (CTCs) in patient blood is seen as a crucial prognostic factor. The potential of CTC analysis is further not limited to the determination of the overall survival rate but sheds light on understanding inter‐ and intratumoral heterogeneity. In this regard, commercial CTC isolation devices combining an efficient enrichment of rare cells with a droplet deposition of single cells for downstream analysis are highly appreciated. The Liquid biopsy platform CTCelect was developed to realize a fully‐automated enrichment and single cell dispensing of CTCs from whole blood without pre‐processing. We characterized each process step with two different carcinoma cell lines demonstrating up to 87 % enrichment (n = 10) with EpCAM coupled immunomagnetic beads, 73 % optical detection and dispensing efficiency (n = 5). 40 to 56.7 % of cells were recovered after complete isolation from 7.5 ml untreated whole blood (n = 6). In this study, CTCelect enabled automated dispensing of single circulating tumor cells from HNSCC patient samples, qPCR‐based confirmation of tumor‐related biomarkers and immunostaining. Finally, the platform was compared to commercial CTC isolation technologies to highlight advantages and limitations of CTCelect. This system offers new possibilities for single cell screening in cancer diagnostics, individual therapy approaches and real‐time monitoring. [ABSTRACT FROM AUTHOR]

The relevance of Hedgehog signaling in Merkel cell carcinoma has only been addressed by a few studies with conflicting results. Thus, we aimed to establish the expression of Hedgehog signaling molecules in Merkel cell carcinoma to characterize causes of aberrant expression and to correlate these findings with the clinical course of the patients. Immunohistochemistry was performed for Sonic, Indian, Patched 1 (PTCH1) and Smoothened on patients' tumor tissue. Respective mRNA expression was analyzed in 10 Merkel cell carcinoma cell lines using quantitative real‐time polymerase chain reaction. PTCH1 sequencing and DNA methylation microarray analyses were carried out on tumor tissues as well as cell lines. PTCH1 immunoreactivity in Merkel cell carcinoma was similar to that of basal cell carcinomas, which both significantly differed from PTCH1 immunoreactivity in healthy skin. Most PTCH1 mutations found were synonymous or without known functional impact. However, on average, the promoter regions of both PTCH1 were hypomethylated independently from PTCH1 gene expression or Merkel cell polyomavirus status. PTCH1 and GLI1/2/3 genes were differently expressed in different cell lines; notably, there was a significant correlation between GLI2 and PTCH1 mRNA expression. Similar to PTCH1 protein expression in patient tissues, PTCH1 gene expression in Merkel cell carcinoma cell lines is highly variable, but due to the similar methylation pattern across Merkel cell carcinoma cell lines, effects other than methylation seem to be the reason for the differential expression and PTCH1 appears to be upregulated by GLI as a classical Hedgehog target gene. [ABSTRACT FROM AUTHOR]

Direct comparisons of the incidence and survival of cutaneous vs mucocutaneous genital squamous cell carcinomas (SCCs) are lacking even though they may bring important insights. We aimed to compare incidence rates and survival of cutaneous and mucocutaneous genital SCCs head‐to‐head, using the same source population, cancer registry methodology and statistical methods in a population of predominantly white Caucasian descent. Using data (2007‐2015) from the population‐based cancer registry of North Rhine‐Westphalia, (population of 18 million people), we estimated age‐specific and age‐standardized (old European standard) incidence rates and age‐standardized relative 5‐year survival of SCC with the period approach for the period 2012 to 2015. Overall, 83 650 SCC cases were registered. The age‐standardized incidence rates (per 100 000 person‐years) of cutaneous SCCs were 36.5 (SE 0.17) and 17.0 (SE 0.11) among men and women, respectively, with corresponding rates for mucocutaneous genital skin, 1.3 (SE 0.03) and 4.5 (SE 0.06) for men and women, respectively. In all age groups, incidence rates of mucocutaneous genital SCCs were higher in women than men. Men had higher cutaneous SCC incidence at all nongenital subsites than women, with the exception of the lower extremities. Five‐year relative survival was considerably lower for mucocutaneous genital SCCs (men: 71%, women: 75%), especially of the scrotal skin (67%) and labia majora (62%) than for SCC of nongenital skin (men: 93%, women: 97%). Given their relatively high incidence together with a lower survival probability, future studies are warranted to establish therapies for advanced mucocutaneous genital SCC, such as immune checkpoint inhibition. What's new? Cutaneous and mucocutaneous genital squamous cell carcinoma (SCC) have distinct risk factors. In particular, unlike cutaneous SSC, mucocutaneous disease affects skin not chronically exposed to ultraviolet radiation. Incidence and survival differences between these diseases are largely unexplored. Here, analyses of cancer registry data from North Rhine‐Westphalia show that genital skin SCCs comprise a substantial proportion of SCCs of the body surface, especially in women. Five‐year relative survival was significantly lower for SCC of mucocutaneous genital skin than non‐genital skin SCC. The relatively high incidence and reduced survival of mucocutaneous genital SCC warrant further investigation for underlying mechanisms and potential therapies. [ABSTRACT FROM AUTHOR]

Spitzoid neoplasms are a challenging group of cutaneous melanocytic proliferations. They are characterized by epithelioid and/or spindle‐shaped melanocytes and classified as benign Spitz nevi (SN), atypical Spitz tumors (AST), or malignant Spitz tumors (MST). The intermediate AST category represents a diagnostically challenging group since on purely histopathological grounds, their benign or malignant character remains unpredictable. This results in uncertainties in patient treatment and prognosis. The molecular properties of Spitzoid lesions, especially their transcriptomic landscape, remain poorly understood, and genomic alterations in melanoma‐associated oncogenes are typically absent. The aim of this study was to characterize their transcriptome with digital mRNA expression profiling. Formalin‐fixed paraffin‐embedded samples (including 27 SN, 10 AST, and 14 MST) were analyzed using the NanoString nCounter PanCancer Pathways Panel. The number of significantly differentially expressed genes in SN vs. MST, SN vs. AST, and AST vs. MST was 68, 167, and 18, respectively. Gene set enrichment analysis revealed upregulation of pathways related to epithelial–mesenchymal transition and immunomodulatory‐, angiogenesis‐, hormonal‐, and myogenesis‐associated processes in AST and MST. A molecular signature of SN vs. MST was discovered based on the top‐ranked most informative genes: NRAS, NF1, BMP2, EIF2B4, IFNA17, and FZD9. The AST samples showed intermediate levels of the identified signature. This implies that the gene signature can potentially be used to distinguish high‐grade from low‐grade AST with a larger study cohort in the future. This combined histopathological and transcriptomic methodology is promising for prospective diagnostics of Spitzoid neoplasms and patient management in dermatological oncology. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Actinic keratoses (AKs) are common lesions in light‐skinned individuals that can potentially progress to cutaneous squamous cell carcinoma (cSCC). Both conditions may be associated with significant morbidity and constitute a major disease burden, especially among the elderly. To establish an evidence‐based framework for clinical decision making, the guidelines for actinic keratosis and cutaneous squamous cell carcinoma were developed using the highest level of methodology (S3) according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF). The guidelines are aimed at dermatologists, general practitioners, ENT specialists, surgeons, oncologists, radiologists and radiation oncologists in hospitals and office‐based settings as well as other medical specialties involved in the diagnosis and treatment of patients with AKs and cSCC. The guidelines are also aimed at affected patients, their relatives, policy makers and insurance funds. In the second part, we will address aspects relating to epidemiology, etiology, surgical and systemic treatment of cSCC, follow‐up and disease prevention, and discuss AKs and cSCC in the context of occupational disease regulations. [ABSTRACT FROM AUTHOR]

Summary: Actinic keratoses (AK) are common lesions in light‐skinned individuals that can potentially progress to cutaneous squamous cell carcinoma (cSCC). Both conditions may be associated with significant morbidity and constitute a major disease burden, especially among the elderly. To establish an evidence‐based framework for clinical decision making, the guideline "actinic keratosis and cutaneous squamous cell carcinoma" was developed using the highest level of methodology (S3) according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF). The guideline is aimed at dermatologists, general practitioners, ENT specialists, surgeons, oncologists, radiologists and radiation oncologists in hospitals and office‐based settings as well as other medical specialties involved in the diagnosis and treatment of patients with AK and cSCC. The guideline is also aimed at affected patients, their relatives, policy makers and insurance funds. In the first part, we will address aspects relating to diagnosis, interventions for AK, care structures and quality‐of‐care indicators. [ABSTRACT FROM AUTHOR]

Zusammenfassung: Aktinische Keratosen (AK) sind häufige Hautveränderungen bei hellhäutigen Menschen mit dem Potenzial, in ein kutanes Plattenepithelkarzinom (PEK) überzugehen. Beide Erkrankungen können mit erheblicher Morbidität verbunden sein und stellen eine große Krankheitslast insbesondere in der älteren Bevölkerung dar. Um eine evidenzbasierte, klinische Entscheidungsfindung zu unterstützen, wurde die Leitlinie "Aktinische Keratose und Plattenepithelkarzinom der Haut" auf der Methodikebene S3 nach dem Regelwerk der AWMF entwickelt. Die Leitlinie richtet sich dabei an Dermatologen, Allgemeinmediziner, HNO‐Ärzte, Chirurgen, Onkologen, Radiologen und Strahlentherapeuten in Klinik und Praxis sowie an andere medizinische Fachgebiete, die sich mit der Diagnose und Behandlung von Patienten mit AK und PEK befassen. Die Leitlinie richtet sich auch an betroffene Patienten, deren Angehörige, politische Entscheidungsträger und Versicherungsgesellschaften. In diesem Teil behandeln wir die Themen Diagnostik, Interventionen bei AK, Versorgungsstrukturen und Qualitätsindikatoren. [ABSTRACT FROM AUTHOR]

Merkel cell carcinoma (MCC), an aggressive neuroendocrine skin tumor, is a polyomavirus‐induced human cancer. To study the causal relationship of MCC carcinogenesis with the integrated Merkel cell polyomavirus (MCPyV) in detail, well‐characterized MCC cell lines are needed. Consequently, in the current study, we established and characterized six MCPyV‐positive MCC cell lines. Microarray‐based comparative genomic hybridization revealed a stable genome carrying only a limited number of chromosomal gains and deletions. All cell lines expressed MCC markers Keratin‐20 and neuron‐specific enolase as well as truncated MCPyV‐encoded large T antigen (LT). For five cell lines, we were able to identify the MCPyV‐integration sites in introns of different genes. The LT‐truncating stop codon mutations and integration sites were affirmed in the respective clinical patient samples. Inverse PCR suggested that three of the cell lines contained MCPyV genomes as concatemers. This notion was confirmed for the two cell lines with known integration sites. Importantly, our observation of distinct stop codon mutations in cell lines with concatemeric MCPyV integration indicates that these LT‐truncating mutations occur before integration. In summary, we provide the detailed characterization of six MCPyV‐positive MCC cell lines, which are likely to serve as valuable tools in future MCC research. What's new? The first human cancer identified to be caused by a polyomavirus was Merkel cell carcinoma (MCC). To study the causal relationship of MCC carcinogenesis with the integrated Merkel cell polyomavirus (MCPyV) in detail, well‐characterized MCC cell lines are needed. Here, the authors established and characterized six Merkel cell polyoma virus (MCPyV)‐positive MCC cell lines. The data provide a work of reference for future MCC research and also suggest that in MCPyV‐driven carcinogenesis the prerequisite MCPyV‐LT truncating stop codon mutations occur before viral integration. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Merkel cell carcinoma (MCC, ICD‐O M8247 / 3) is a rare malignant primary skin tumor with epithelial and neuroendocrine differentiation. The neoplastic cells share many morphological, immunohistochemical and ultrastructural characteristics with Merkel cells of the skin. The diagnosis of MCC is rarely made on clinical grounds. Histological and immunohistochemical studies are usually required to confirm the clinical suspicion. Given the frequent occurrence of occult lymph node metastasis, sentinel lymph node biopsy should be performed once distant metastasis has been ruled out by cross‐sectional imaging. Primary tumors without evidence of organ metastases are treated with complete surgical excision with appropriate surgical margins. Radiation therapy should be considered at all stages of the disease. For advanced MCC that is no longer amenable to curative treatment by surgery or radiation therapy, there is currently no established systemic therapy for which an improvement in recurrence‐free survival or overall survival has been demonstrated in a prospective randomized trial. However, immunotherapy using PD‐1/PD‐L1 blockade seems to be superior to chemotherapy. Various factors warrant that further diagnostic and therapeutic interventions be determined by an interdisciplinary tumor board. These factors include the tumor's aggressiveness, the frequent indication for sentinel lymph node biopsy along with the frequent occurrence in the head and neck region, the potential indication for adjuvant radiation therapy as well as the complexity of the required diagnostic workup. [ABSTRACT FROM AUTHOR]

The identification of targetable molecules in cellular signaling pathways represents a milestone in the treatment of melanoma. Selective inhibitors of these molecules, known as phosphokinases, allow for individual signaling pathways to be 'switched off'. This is of particular importance for tumors in which these pathways are constitutively activated by mutations in genes encoding said molecules. Especially patients with BRAF-mutated melanomas significantly benefit from kinase inhibitor therapies, with the current standard of combined BRAF and MEK inhibition providing very good long-term disease control. Such regimens have been shown to achieve a progression-free survival of more than ten months and an overall survival of more than two years, along with good quality of life. Given that the majority of patients develop secondary resistance during long-term kinase inhibitor therapy, current clinical trials are geared towards finding suitable drug combinations including inhibitors of other signaling pathways as well as immune checkpoint inhibitors. The present review highlights targeted therapies for melanoma currently available as well as potential future options presently under clinical investigation. [ABSTRACT FROM AUTHOR]

Zusammenfassung Die Behandlungsstrategie beim metastasierten Melanom hat sich mit der Identifizierung therapeutisch angreifbarer molekularer Zielstrukturen innerhalb zellulärer Signalwege radikal geändert. Durch die Zulassung von Substanzen, die gezielt an den zentralen Schaltmolekülen, den Phosphokinasen, angreifen, können diese Signalwege selektiv abgeschaltet werden. Dies ist insbesondere bei denjenigen Tumoren von Interesse, deren Signalwege durch aktivierende Mutationen der für die Schaltmoleküle kodierenden Gene konstitutiv aktiviert sind. Aktuell ist diese therapeutische Strategie insbesondere für Patienten bedeutsam, deren Melanome eine Mutation im BRAF-Gen aufweisen. Diese Patienten können durch eine Kombinationstherapie aus Inhibitoren der Phosphokinasen BRAF und MEK langfristig mit sehr guter Krankheitskontrolle behandelt werden. Unter dieser Kombinationstherapie wird aktuell ein progressionsfreies Überleben von über zehn Monaten und ein Gesamtüberleben von mehr als zwei Jahren bei guter Lebensqualität erzielt. Da unter längerfristiger Therapie mit Kinaseinhibitoren jedoch bei einem Großteil der Patienten eine Resistenzbildung auftritt, sind aktuelle klinische Therapiestudien auf die Suche nach geeigneten Kombinationspartnern unter Blockierung anderer Signalwege oder unter Aktivierung der T-Zell-vermittelten Immunantwort ausgerichtet. Der vorliegende Übersichtsartikel stellt sowohl die aktuell verfügbaren als auch die in der klinischen Testung befindlichen zukünftigen Optionen der zielgerichteten Therapie des Melanoms dar. [ABSTRACT FROM AUTHOR]

Abstract: In vivo tumor models are essential for studying the biology of cancer, identifying tumor targets and evaluating antitumor drugs. Considering the request for the minimisation of animal experiments and following the “3R”‐rule (“replacement,” “refinement,” “reduction”), it has become crucial to develop alternative experimental models in cancer biology. Several studies have already described the avian chorioallantoic membrane (CAM) model as an alternative to rodents, suitable to investigate growth, progression and metastasis of various types of cancer. In the present work, we grafted three Merkel cell carcinoma (MCC) cell lines onto the avian CAM and monitored tumor growth and development of solid tumor nodules. Morphology of xenograft was characterised histologically and immunohistochemically. Our results demonstrate CAM assay as a useful tool to study MCC pathophysiology. [ABSTRACT FROM AUTHOR]

Primary cutaneous large B-cell lymphomas, leg type ( PCLBCL/ LT) are primary cutaneous B-cell lymphoma ( PCBCL) with an intermediate prognosis. Therefore, antracycline-based polychemotherapy combined with rituximab has been recommended as first-line treatment. Yet, despite this regimen, the 5-year survival rate remains 50-66% only. Angiogenesis, the formation of a vascular network, is essential for the pathogenesis of nodal lymphomas. So far, no study has analysed angiogenesis and its key factors in PCLBCL/ LT. The present study was aimed at characterizing angiogenesis in PCLBCL/ LT to identify the angiogenic molecules as potential therapeutic targets. The intra-tumoral microvessel density ( MVD) was assessed by immunohistochemical studies of CD20 and CD31. The MVD was higher in PCLBCL/ LT compared with indolent PCBCL. Analyses of open-source microarray data showed correlation between the angiogenic molecule angiopoietin-2 (Ang-2) and pan-endothelial cell markers. ELISA studies determined a shift between Ang-2 and Ang-1 towards Ang-2 in the peripheral blood of PCLBCL/ LT patients. Immunofluorescence costainings against the Ang receptor Tie2/angiogenic integrins/ CD34 revealed that the vasculature in both aggressive and indolent PCBCL tumors harbours an endothelial cell subpopulation with reduced expression of Tie2. In contrast, the alternative Ang-2 binding partners, angiogenic integrins, are strongly expressed in PCBCL. In line with these findings, downstream targets of Ang-2-integrin signalling, that is phosphorylation of focal adhesion kinase at Tyr397, and sprouting angiogenesis are enhanced in PCLBCL/ LT. Our data present Ang-2 as a promising therapeutic target and anti-angiogenic therapy as a new line in treatment of PCLBCL/ LT as a hitherto intractable disease. [ABSTRACT FROM AUTHOR]

The Merkel cell polyomavirus (MCPyV) is detected in 80% of Merkel cell carcinomas (MCC). Clonal integration and tumor-specific mutations in the large T antigen are strong arguments that MCPyV is a human tumor virus. However, the relationship between viral presence and cancer induction remains discussed controversially. Since almost all studies on virus prevalence are based on PCR techniques, we performed MCPyV fluorescence in situ hybridization (FISH) on MCC to gain information about the quality of the viral presence on the single cell level. MCPyV-FISH was performed on tissue microarrays containing 62 formalin-fixed and paraffin-embedded tissue samples including all tumor grades of 42 patients. The hybridization patterns were correlated to the qPCR data determined on corresponding whole tissue sections. Indeed, MCPyV-FISH and qPCR data were highly correlated, i.e. 83% for FISH-positive and 93% for FISH-negative cores. Accordingly, the mean of the qPCR values of all MCPyV-positive cores differed significantly from the mean of the negative cores ( p = 0.0076). Importantly, two hybridization patterns were definable in the MCPyV-FISH: a punctate pattern (85%) indicating viral integration, which correlated with a moderate viral abundance and a combination of the punctate with a diffuse pattern (15%), suggesting a possible coexistence of integrated and episomal virus which was associated with very high viral load and VP1 expression. Thus, MCPyV-FISH adds important information on the single cell level within the histomorphological context and could therefore be an important tool to further elucidate MCPyV related carcinogenesis. [ABSTRACT FROM AUTHOR]

Background: Systemic treatment with pegylated liposomal doxorubicin is an established second-line treatment of advanced cutaneous T-cell lymphoma. Pegylated liposomal doxorubicin (PLD) is currently unavailable, therefore, clinical studies investigating the efficacy of non-pegylated liposomal formula (NPLD) have been analyzed. Methods: Since clinical trials comparing PLD and NPLD in CTCL do not exist, the clinical use of NPLD including safety and efficiency profile in other types of non-Hodgkin lymphoma were analyzed. Results: Clinical trials show a comparable efficacy of NPLD and PLD in non-Hodgkin lymphoma. The dosage of NPLD used in the treatment of systemic lymphoma within polychemotherapy regimens was 50 mg/m2 every three weeks. Overall response was 75-95%, including a complete remission rate of 65-80% and 2- and 3-year overall survival rates of 55-75%. These data indicate that the non-pegylated formula of doxorubicin has a similar antitumor effect as the pegylated one but shows reduced cardiotoxicity. The palmoplantar erythrodysesthesia frequently observed in PLD has not been observed with the use of the NPLD. Conclusions: The clinical use of NPLD in the treatment of CTCL is reasonable. In analogy to the clinical trials of NPLD in non-Hodgkin lymphoma a dosage of 50 mg/m2 every three weeks is recommended for the treatment of CTCL. [ABSTRACT FROM AUTHOR]

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer that frequently harbours Merkel cell polyomavirus (MCV) DNA integrated in the genome of the tumor cells. In our study, we elaborate our recent finding that MCV-positive MCC cell lines require the expression of the viral T antigens (TA). Indeed, in a xeno-transplantation model, we prove that TA expression is essential also in an in vivo situation, as knock down of TA leads to tumor regression. Moreover, rescuing TA short hairpin RNA (shRNA)-treated MCV-positive MCC cells by ectopic expression of shRNA-insensitive TAs clearly demonstrates that the observed effect is caused by TA knockdown. Notably, introduction of a mutation in the LTA protein interfering with LTA binding to the retinoblastoma protein (RB) ablated this rescue. The importance of this interaction was further confirmed as LTA-specific knockdown leads to explicit cell growth inhibition. In summary, the presented data demonstrate that established MCV-positive MCC tumors critically depend on TA expression, in particular the LTA and RB interaction, for sustained tumor growth. Consequently, interference with LTA/RB interaction appears as promising strategy to treat MCC. [ABSTRACT FROM AUTHOR]

Inhibitors of the epidermal growth factor receptor (EGFR) are increasingly used in the treatment of various entities of malignant tumors. Patients treated with EGFR inhibitors very likely develop cutaneous side effects. The development of a papulopustular, follicular exanthema during the first weeks of therapy correlates with therapeutic benefit. However, this exanthema and other cutaneous side effects can impair the quality of life of the patient and might limit the therapy with the EGFR inhibitor. For an optimal therapeutic benefit and quality of life an adequate management of cutaneous side effects is necessary. A panel of German dermatologists developed on the basis of personal experience and current literature consensus recommendations for the management of cutaneous side effects of EGFR inhibitors. [ABSTRACT FROM AUTHOR]

Werling A M, Doerflinger Y, Brandner J M, Fuchs F, Becker J C, Schrama D, Kurzen H, Goerdt S & Peitsch W K (2011) Histopathology 286-303 Merkel cell carcinomas (MCCs) are rare but aggressive tumours associated recently with Merkel cell polyomavirus (MCV). As development and progression of several types of carcinomas can be promoted by changes in cell adhesion proteins, the aim of this study was to examine homo- and heterotypic cell contacts of Merkel cells and MCCs. Merkel cells of healthy glabrous epidermis and 52 MCCs were analysed by double-label immunostaining, immunofluorescence and confocal microscopy. Merkel cells were connected to keratinocytes by E- and P-cadherin, desmoglein 2 and desmocollin 2. In contrast, the vast majority of MCCs (90%) contained N-cadherin, but only 67% and 65% contained E- and P-cadherin, respectively. Interestingly, P-cadherin was absent significantly more frequently in lymph node metastases than in primary tumours and by trend in more advanced clinical stages. Moreover, major subsets of MCCs synthesized desmoglein 2 and, surprisingly, tight junction proteins. No significant differences were observed upon stratification for MCV DNA, detected in 84% of tumours by real-time polymerase chain reaction. Assuming that MCCs originate from Merkel cells, our data indicate a switch from E- and P-cadherin to N-cadherin during tumorigenesis. Whether the unexpected heterogeneity of junctional proteins can be exploited for prognostic and therapeutic purposes will need to be examined. [ABSTRACT FROM AUTHOR]

Please cite this paper as: A novel xenograft model of cutaneous T-cell lymphoma. Experimental Dermatology 2010; : 1096-1102. Cutaneous T-cell lymphomas (CTCLs) are characterized by accumulation of malignant T cells in the skin. Early disease resembles benign skin disorders but during disease progression cutaneous tumors develop, and eventually the malignant T cells can spread to lymph nodes and internal organs. However, because of the lack of suitable animal models, little is known about the mechanisms driving CTCL development and progression in vivo. Here, we describe a novel xenograft model of tumor stage CTCL, where malignant T cells (MyLa2059) are transplanted to NOD/SCID-B2m (NOD.Cg-Prkdc B2m/J) mice. Subcutaneous transplantation of the malignant T cells led to rapid tumor formation in 43 of 48 transplantations, whereas transplantation of non-malignant T cells isolated from the same donor did not result in tumor development. Importantly, the tumor growth was significantly suppressed in mice treated with vorinostat when compared to mice treated with vehicle. Furthermore, in most mice the tumors displayed subcutaneous and/or lymphatic dissemination. Histological, immunohistochemical and flow cytometric analyses confirmed that both tumors at the inoculation site, as well as distant subcutaneous and lymphatic tumors, originated from the transplanted malignant T cells. In conclusion, we describe a novel mouse model of tumor stage CTCL for future studies of disease dissemination and preclinical evaluations of new therapeutic strategies. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Mouse models for melanoma: a personal perspective. Experimental Dermatology 2010; 19: 157–164. Complex biological processes often require in vivo analysis, and many important research advances have been made using mice as a model for the study of various biological systems. Cutaneous melanomas are tumors originating from skin melanocytes, which are present in hair follicles, and interfollicular epidermal and dermal layers. Until recently, mouse melanoma models were largely based on transplantation models, i.e. transplantation of either syngeneic or xenogeneic melanoma cells into wild type or genetically modified animals. More recently, however, the use of novel technologies specifically modifying the genome allows for the generation of mouse strains, which may develop spontaneous melanoma. Nevertheless, it should be kept in mind that animal models provide only an approximation of reality in humans. In this review, we will discuss a representative selection of currently available transplantation and transgenic melanoma models; despite the fact that this selection will be biased by personal experience, we are confident to demonstrate how the use of mouse melanoma models facilitates translational research in several biomedical disciplines. [ABSTRACT FROM AUTHOR]

Merkel cell polyomavirus (MCV) is a newly-discovered human tumor virus found in ∼80% of Merkel cell carcinoma (MCC). The rate of MCV infection among persons without MCC is unknown. We developed a MCV virus-like particle (VLP) enzyme-linked immunoassay (EIA) that does not cross-react with human BK or murine polyomaviruses. Peptide mapping of the MCV VP1 gene and immunoblotting with denatured MCV VLP are less sensitive than the MCV EIA in detecting MCV antibodies suggesting antibody reactivity in this assay primarily targets conformational but not linear epitopes. Among MCC patients, all 21 (100%) patients tested with MCV-positive tumors had high serum MCV IgG but not high MCV IgM levels. Only 3 of 6 (50%) MCC patients with MCV-negative tumors were positive for MCV antibodies. Sera from most adults, including 107 of 166 (64%) blood donors, 63 of 100 (63%) commercial donors and 37 of 50 (74%) systemic lupus erythematosus patients, show evidence for prior MCV exposure. Age-specific MCV prevalence was determined by examining a cross-sectional distribution of 150 Langerhans cell histiocytosis (an unrelated neoplasm) patient sera. MCV prevalence increases from 50% among children age 15 years or younger to 80% among persons older than 50 years. We did not find evidence for vertical transmission among infants. Although past exposure to MCV is common among all adult groups, MCC patients have a markedly elevated MCV IgG response compared with control patients. Our study demonstrates that MCV is a widespread but previously unrecognized human infection. © 2009 UICC [ABSTRACT FROM AUTHOR]

Background: Merkel cell carcinoma is a rare skin cancer of neuroendocrine origin, which is characterized by a high rate of recurrence, metastatic spread and mortality. Because of its rarity, evidence-based therapeutic regimens are difficult to establish. Merkel cell carcinoma is known to be both radio- and chemosensitive. Toxicity is a key factor in assessing any regimen, as the patients are usually elderly and likely to have other significant medical problems. Patients and Methods: We retrospectively evaluated five patients with metastatic Merkel cell carcinoma to see if liposomal doxorubicin (Caelyx® or Myocet®) in combination with radiotherapy exhibited clinical anti-tumoral effects accompanied by acceptable side effects. Results: The outpatient chemotherapy regimen was tolerated without major side effects and produced good response rates. All patients achieved at least tumor stabilization; four of five had a partial remission. Effects of therapy were usually seen in the first cycle of therapy but the responses were of short duration with an average interval of two months until progression. Conclusions: As combined radiochemotherapy with liposomal doxorubicin is well tolerated even in older patients with other illnesses and can be given on an outpatient basis, it is an attractive option for metastatic Merkel cell carcinoma. Based on response rate or overall survival, it offers no advantages compared to polychemotherapy. [ABSTRACT FROM AUTHOR]