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The diagnosis of Sézary syndrome (SS) relies on the identification of blood Sézary cells (SC) by different markers via flow cytometry. Treatment of SS is challenging since its pathogenesis is characterized by cell death resistance rather than hyperproliferation. In this study, we establish an integrated approach that considers both the expression of SC markers and sensitivity to cell death both spontaneously and upon in vitro treatment. Peripheral blood mononuclear cells were isolated from 20 SS patients and analysed for the SC markers CD7 and CD26 loss as well as CD158k and PD1 gain. The cells were then treated with different established and experimental therapies in vitro and cell death was measured. Spontaneous and therapeutically induced cell death were measured and correlated to cellular marker profiles. In the marker‐positive cells, spontaneous cell death sensitivity was reduced. Different treatments in vitro managed to specifically induce cell death in the putative CTCL cell populations. Interestingly, a repeated analysis after 3 months of treatment revealed the CTCL cell death sensitivity to be restored by therapy. We propose this novel integrated approach comprising the evaluation of SC marker expression and analysis of cell death sensitivity upon treatment that can also enable a better therapy stratification. [ABSTRACT FROM AUTHOR]

Background: Primary cutaneous B-cell lymphomas (CBCL) are a group of rare malignant skin diseases that represent approximately 20%--30% of all primary cutaneous lymphomas (PCL). Previous studies revealed impaired health-related quality of life (HRQoL) in patients diagnosed with primary cutaneous T-cell lymphoma (CTCL). Currently, only small-sized studies investigated HRQoL in CBCL patients and lacked detailed analysis of respective subtypes. Objectives: This study aims to investigate HRQoL in CBCL patients to identify independent factors of HRQoL impairment in CBCL patients. Methods: One hundred CBCL patients were recruited from eight German PCL centres in this multicentric, cross-sectional study from 2021 to 2022. The patients completed the dermatologic HRQoL questionnaire Skindex-29 and an investigator-designed 'CBCL-Questionnaire' with additional questions on HRQoL and clinical characteristics. Results: The Skindex-29 revealed that HRQoL in CBCL patients is impaired on a mild to moderate level. The multiple regression analysis identified parameters like worries about dying, feeling prejudiced/discriminated and impairment of daily activities to be independently associated with impairment of HRQoL. Highest scores for HRQoL impairment were found in patients with primary cutaneous follicle centre lymphoma while on rituximab treatment and in patients with primary cutaneous marginal zone lymphoma while on watchful waiting. Conclusions: HRQoL is impaired in CBCL patients, even though, in the face of indolent disease course and favourable prognosis in the majority of cases. Of note, our investigator-designed tool identified worries about dying, feeling prejudiced/discriminated, and the type of treatment to have a negative impact on patients' HRQoL. Our study highlights the importance of a thorough patient--doctor communication to capture overall disease burden because generic HRQoL tools might lack of disease-specific items. [ABSTRACT FROM AUTHOR]

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common subtypes of the heterogeneous group of cutaneous T-cell lymphomas (CTCL). With the expansion of the biologic treatment landscape, new treatment options have become available in recent years, most notably the C-C chemokine receptor 4 (CCR4)-directed monoclonal antibody mogamulizumab. Based on the phase III pivotal trial, mogamulizumab is recommended by the German S2k guidelines for the second-line treatment of stage IB and above SS and MF, after at least one prior systemic therapy. Since then, new insights on safety and efficacy of mogamulizumab were generated by post hoc analyses and real-world evidence. A panel of CTCL-experts discussed available literature and own experiences and developed relevant recommendations on the use of mogamulizumab in clinical practice in Germany. The recommendations cover patient criteria, prior therapies, use of mogamulizumab as monotherapy or combination therapy, management of side effects, duration of therapy, and monitoring schedules. The aim of these clinical recommendations is to support healthcare professionals in their decision-making and use of mogamulizumab in daily practice., (© 2024 The Author(s). Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft.)

Purpose: We aim to determine the current treatment patterns and recommendations among physicians for cutaneous lymphomas and to identify the types of skin lymphomas for which existing radiation regimens need improvement., Methods and Materials: A questionnaire from the European Organisation for Research and Treatment of Cancer was distributed to all members of the Cutaneous Lymphoma Tumour Group and Radiation Oncology Scientific Council. This online survey included 13 questions regarding treatment practices for patients with cutaneous lymphoma. The survey was conducted from August 21 to December 18, 2023. Frequency distributions and subgroup comparisons were calculated and analyzed., Results: We collected 51 completed questionnaires from investigators from 19 countries specializing in cutaneous lymphoma treatment. Radiation doses varied significantly (range, 4-60 Gy). Based on the histologic entity, up to one-third of the investigators delivered hypofractionated regimens (range, 14%-35%). Reduced-dose radiation therapy (RT) was considered by 27% to 63% of investigators. Meanwhile, 18 (35%) investigators considered adapting the radiation dose to the response to immunochemotherapy when treating primary cutaneous diffuse large B cell lymphoma-leg type. Regarding total skin electron beam therapy, 91% of centers delivered reduced-dose regimens, and 18% of investigators applied ultrahypofractionated protocols., Conclusions: RT in patients with cutaneous lymphoma is highly heterogeneous among the European Organisation for Research and Treatment of Cancer centers. The development of evidence-based recommendations for RT dose, fractionation, and technique for cutaneous lymphomas is required for optimization and standardization of treatment., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Interferon-alpha is an important therapeutic option for the treatment of the cutaneous T-cell lymphomas (CTCL). Since the approved recombinant interferon-α-2a (IFN-α2a) has no longer been produced since January 2020, pegylated interferon-α2a (pegIFN-α2a) can be used as an alternative treatment, even though it is not approved for the treatment of CTCL. The aim of this multicentre study was to generate comprehensive data on the efficacy and tolerability of pegIFN-α2a in the treatment of CTCL., Patients and Methods: A multicenter retrospective study was conducted with 70 patients with CTCL from twelve German skin centers., Results: In total, 70 patients were included in the study, with 57.2% male and a mean age of 58.8 ± 14.9 years. Mycosis fungoides was present in 71.4% of cases and Sézary Syndrome in 28.6%. An overall response rate of 55.2% was observed with pegIFNα-2a therapy. In 50% of cases, therapy was discontinued after 63.6 ± 33.5 weeks. The most common reason for discontinuation was adverse events, which occurred in 68.6% of cases and which were classified as severe in 29.2%. Blood count changes, fatigue and liver toxicity occurred most frequently., Conclusions: Our analysis provides comprehensive data on the efficacy and tolerability of pegIFNα-2a therapy in patients with CTCL. In terms of response rates and side effect profile, pegIFNα-2a appears to be comparable to IFN-α2a therapy., (© 2024 The Author(s). Journal der Deutschen Dermatologischen Gesellschaft published by Wiley‐VCH GmbH on behalf of Deutsche Dermatologische Gesellschaft.)

Background: Primary cutaneous acral CD8+ T-cell lymphoproliferative disorder (TLPD) is a rare and indolent lymphoma entity. Although TLPD was first identified many years ago, the molecular pathogenesis is still not fully understood., Objectives: In order to better understand the molecular pathogenesis of cutaneous acral CD8+ TLPD and to identify further discriminatory markers to differentiate this lymphoma subtype from other CD8+ cutaneous lymphomas, we analysed five cases of cutaneous acral CD8+ TLPD for putative molecular alterations., Methods: Somatic alterations were assessed using whole-exome and targeted sequencing of paraffin-embedded tissue. Results were evaluated using immunohistochemical staining of respective relevant proteins. CD8+ cutaneous T-cell lymphomas (n = 12) served as control for KIR3DL1 staining., Results: Copy number variation analysis revealed a homozygous deletion of the KIR3DL1 gene in two of the analysed cases. This resulted in loss of KIR3DL1 protein expression, which was observed in all cases of cutaneous acral CD8+ TLPD. In contrast, KIR3DL1 expression was more variable in other CD8+ cutaneous T-cell lymphomas with 50% of analysed cases (n = 12) found to be positive. In addition, one further case of acral CD8+ TLPD harboured a loss-of-function mutation in the PIK3R1 gene, presumably activating the phosphoinositide 3-kinase-AKT pathway., Conclusions: Alterations of the KIR3DL1 gene may be of pathogenetic relevance for acral CD8+ TLPD. Loss of KIR3DL1 protein expression may support the diagnosis of this indolent lymphoma entity; however, this is not a subtype-specific discriminative feature., Competing Interests: Conflicts of interest The authors declare they have no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT) is a subtype of cutaneous B-cell lymphoma with unfavorable prognosis usually requiring aggressive polychemotherapy for disease control. Only single cases of spontaneous regression of PCDLBCL, LT are reported in the literature, peaking 3 months post-biopsy following a clinical history of no longer than 1 year. Here, we report the first case of a spontaneously relapsing and remitting PCDLBCL, LT with complete regression after a clinical history of more than 9 years and thus an atypically indolent clinical course. The female patient presented with recurrent erythematous, non-ulcerated, non-raised plaques of the right lower leg for 6 years. Pathological workup and exclusion of a systemic disease confirmed the diagnosis of PCDLBCL, LT. Due to the history of repeated spontaneous remission, no therapy was initiated. Nine years after first occurrence the patient presented with complete clinical remission lasting for 64 months. We retrospectively identified four additional PCDLBCL, LT patients with spontaneous remission lasting up to 53 months. Our data provide evidence for a distinct PCDLBCL, LT patient subgroup that clinicians should be aware of and warrants a watch-and-wait treatment regime., (© 2024 The Author(s). The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.)

Abstract: Patients with Sézary syndrome (SS), a leukemic variant of cutaneous T-cell lymphoma (CTCL), are prone to Staphylococcus aureus infections and have a poor prognosis due to treatment resistance. Here, we report that S aureus and staphylococcal enterotoxins (SE) induce drug resistance in malignant T cells against therapeutics commonly used in CTCL. Supernatant from patient-derived, SE-producing S aureus and recombinant SE significantly inhibit cell death induced by histone deacetylase (HDAC) inhibitor romidepsin in primary malignant T cells from patients with SS. Bacterial killing by engineered, bacteriophage-derived, S aureus-specific endolysin (XZ.700) abrogates the effect of S aureus supernatant. Similarly, mutations in major histocompatibility complex (MHC) class II binding sites of SE type A (SEA) and anti-SEA antibody block induction of resistance. Importantly, SE also triggers resistance to other HDAC inhibitors (vorinostat and resminostat) and chemotherapeutic drugs (doxorubicin and etoposide). Multimodal single-cell sequencing indicates T-cell receptor (TCR), NF-κB, and JAK/STAT signaling pathways (previously associated with drug resistance) as putative mediators of SE-induced drug resistance. In support, inhibition of TCR-signaling and Protein kinase C (upstream of NF-κB) counteracts SE-induced rescue from drug-induced cell death. Inversely, SE cannot rescue from cell death induced by the proteasome/NF-κB inhibitor bortezomib. Inhibition of JAK/STAT only blocks rescue in patients whose malignant T-cell survival is dependent on SE-induced cytokines, suggesting 2 distinct ways SE can induce drug resistance. In conclusion, we show that S aureus enterotoxins induce drug resistance in primary malignant T cells. These findings suggest that S aureus enterotoxins cause clinical treatment resistance in patients with SS, and antibacterial measures may improve the outcome of cancer-directed therapy in patients harboring S aureus., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Targeted therapies for cutaneous T-cell lymphoma (CTCL) are limited and curative approaches are lacking. Furthermore, relapses and drug induced side effects are major challenges in the therapeutic management of patients with CTCL, creating an urgent need for new and effective therapies. Pathologic constitutive NF-κB activity leads to apoptosis resistance in CTCL cells and, thus, represents a promising therapeutic target in CTCL. In a preclinical study we showed the potential of dimethyl fumarate (DMF) to block NF-κB and, specifically, kill CTCL cells. To translate these findings to applications in a clinical setting, we performed a multicentric phase 2 study evaluating oral DMF therapy in 25 patients with CTCL stages Ib to IV over 24 weeks (EudraCT number 2014-000924-11/NCT number NCT02546440). End points were safety and efficacy. We evaluated skin involvement (using a modified severity weighted assessment tool [mSWAT]), pruritus, quality of life, and blood involvement, if applicable, as well as translational data. Upon skin analysis, 7 of 23 (30.4%) patients showed a response with >50% reduction in the mSWAT score. Patients with high tumor burden in the skin and blood responded best to DMF therapy. Although not generally significant, DMF also improved pruritus in several patients. Response in the blood was mixed, but we confirmed the NF-κB-inhibiting mechanism of DMF in the blood. The overall tolerability of the DMF therapy was very favorable, with mostly mild side effects. In conclusion, our study presents DMF as an effective and excellently tolerable therapeutic option in CTCL to be further evaluated in a phase 3 study or real-life patient care as well as in combination therapies. This trial was registered at www.clinicaltrials.gov as #NCT02546440., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Leukemic cutaneous T-cell lymphomas (L-CTCL) are lymphoproliferative disorders of skin-homing mature T-cells causing severe symptoms and high mortality through chronic inflammation, tissue destruction, and serious infections. Despite numerous genomic sequencing efforts, recurrent driver mutations have not been identified, but chromosomal losses and gains are frequent and dominant. We integrated genomic landscape analyses with innovative pharmacologic interference studies to identify key vulnerable nodes in L-CTCL. We detected copy number gains of loci containing the STAT3/5 oncogenes in 74% (n = 17/23) of L-CTCL, which correlated with the increased clonal T-cell count in the blood. Dual inhibition of STAT3/5 using small-molecule degraders and multi-kinase blockers abolished L-CTCL cell growth in vitro and ex vivo, whereby PAK kinase inhibition was specifically selective for L-CTCL patient cells carrying STAT3/5 gains. Importantly, the PAK inhibitor FRAx597 demonstrated encouraging anti-leukemic activity in vivo by inhibiting tumor growth and disease dissemination in intradermally xenografted mice. We conclude that STAT3/5 and PAK kinase interaction represents a new therapeutic node to be further explored in L-CTCL., (© 2022 The Authors. Published under the terms of the CC BY 4.0 license.)

Background: Primary cutaneous follicular B-cell lymphoma (PCFBCL) represents an indolent subtype of Non-Hodgkin's lymphomas, being clinically characterized by slowly growing tumors of the skin and common cutaneous relapses, while only exhibiting a low propensity for systemic dissemination or fatal outcome. Up to now, only few studies have investigated underlying molecular alterations of PCFBCL with respect to somatic mutations., Objectives: Our aim was to gain deeper insight into the pathogenesis of PCFBCL and to delineate discriminatory molecular features of this lymphoma subtype., Methods: We performed hybridization-based panel sequencing of 40 lymphoma-associated genes of 10 cases of well-characterized PCFBCL. In addition, we included two further ambiguous cases of atypical B-cell-rich lymphoid infiltrate/B-cell lymphoma of the skin for which definite subtype attribution had not been possible by routine investigations., Results: In 10 out of 12 analyzed cases, we identified genetic alterations within 15 of the selected 40 target genes. The most frequently detected alterations in PCFBCL affected the TNFRSF14 , CREBBP , STAT6 and TP53 genes. Our analysis unrevealed novel mutations of the BCL2 gene in PCFBCL. All patients exhibited an indolent clinical course. Both the included arbitrary cases of atypical B-cell-rich cutaneous infiltrates showed somatic mutations within the FAS gene. As these mutations have previously been designated as subtype-specific recurrent alterations in primary cutaneous marginal zone lymphoma (PCMZL), we finally favored the diagnosis of PCMZL in these two cases based on these molecular findings., Conclusions: To conclude, our molecular data support that PCFBCL shows distinct somatic mutations which may aid to differentiate PCFBCL from pseudo-lymphoma as well as from other indolent and aggressive cutaneous B-cell lymphomas. While the detected genetic alterations of PCFBCL did not turn out to harbor any prognostic value in our cohort, our molecular data may add adjunctive discriminatory features for diagnostic purposes on a molecular level.

Pyogenic granuloma is one of the most common vascular tumours. The cause of pyogenic granuloma was previously thought to be an inflammatory reaction with consecutive stimulation of endothelial cell proliferation. However, recent studies suggest that pyogenic granuloma may be driven by constitutive activation of the mitogen-activated protein kinase pathway. The aim of this study was to investigate the molecular profile of sporadic pyogenic granuloma of childhood, using a systematic approach scrutinizing potential aberrations within different oncogenic pathways. Within a retrospective setting pyogenic granuloma of 15 patients was analysed by targeted next generation sequencing using the Oncomine Focus Assay, which includes genes of key tumorigenic signalling pathways. Activating mutations were found in 4 out of 15 cases (27%). Two HRAS hotspot mutations (p.Gly13Arg, p.Ala59Thr), 1 BRAF (p.Val600Glu) mutation and a novel, previously not reported, MAP2K1 hotspot mutation (p.Glu203Lys) were identified. It is notable that all of these genes are involved in constitutive mitogen- activated protein kinase signalling. This study increases the range of underlying genetic alterations in pyogenic granuloma by identifying novel oncogenic mutations in crucial mitogen-activated protein kinase pathway genes. The results provide supporting evidence that activated mitogen-activated protein kinase signalling is a key driver in the pathogenesis of pyogenic granuloma, which might be exploited by targeted treatment approaches for selected cases.

Background: Rhabdoid melanoma is a rare variant of malignant melanoma with characteristic cytomorphologic features. Due to the potential loss of conventional melanocytic markers, histopathologic diagnosis is often challenging. We hypothesize that immunostaining for PReferentially expressed Antigen in MElanoma (PRAME) might have the potential to uncover the melanocytic origin of these dedifferentiated tumors., Methods: Four cases of rhabdoid primary melanomas were assessed by immunohistochemistry for expression of PRAME and conventional melanocytic markers. Immunohistochemical expression patterns were analyzed in the rhabdoid primaries and, if available, associated metastases., Results: All four cases of rhabdoid primary melanomas showed a strong nuclear positivity for PRAME, while the expression of conventional melanocytic markers S100, MART-1, SOX-10 and HMB-45 was variable between the analyzed cases., Conclusions: In summary, we report four cases of rhabdoid primary melanoma with high to intermediate expression of PRAME despite the partial and variable loss of other melanocytic markers. Hence, PRAME might facilitate the recognition of this highly aggressive entity to avoid misdiagnosis due to histopathologic pitfalls.

Background: The differential diagnosis of atypical dermal nonepidermotropic CD8 + lymphocytic infiltrates includes a heterogeneous spectrum of lymphoproliferations with overlapping histological and phenotypic features, but divergent clinical manifestations and prognoses. As these neoplasms are rare, more data on their clinicopathological presentation and course are needed., Objectives: To assess the clinical, histological and immunophenotypic features; outcomes of; and differences between dermal CD8 + lymphoproliferations., Methods: Retrospective analysis of a series of 46 patients and biopsies by the international EORTC Cutaneous Lymphoma Group., Results: The dermal CD8 + lymphoproliferations (n = 46) could be assigned to one of three groups: (i) cutaneous acral CD8 + T-cell lymphoma (n = 31), characterized mostly by a solitary nodule arising at acral sites, a monotonous dermal infiltrate of small-to-medium-sized CD8 + lymphocytes with a characteristic dot-like pattern of CD68, a low proliferation rate and an excellent prognosis; (ii) primary cutaneous CD8 + peripheral T-cell lymphoma, unspecified/NOS (n = 11), presenting with one or multiple rapidly evolving tumours, mostly medium-sized pleomorphic CD8 + tumour cells with expression of several cytotoxic markers, and high proliferative activity; and (iii) cutaneous CD8 + lymphoproliferations (n = 4), associated with congenital immunodeficiency syndromes in two patients with persisting localized or disseminated violaceous to brownish plaques on the extremities, a histiocyte-rich infiltrate of mostly small CD8 + lymphocytes with subtle atypia and a protracted course; and papular CD8 + eruptions in two patients with acquired immunosuppression., Conclusions: A constellation of distinct clinical, histopathological and phenotypic features allows discrimination and assignment of dermal CD8 + infiltrates into distinct disease entities. Primary cutaneous acral CD8 + lymphoma, assigned a provisional category in current lymphoma classifications, is a distinct and reproducible entity. A correct diagnosis is essential to avoid unnecessarily aggressive treatment for indolent CD8 + lymphoproliferations and to identify cases with underlying immuno-deficiency or potential for dismal outcome., (© 2022 British Association of Dermatologists.)

Background: In Europe chlormethine gel is licensed for the management of patients with mycosis fungoides of all stages. However, the optimal regimen regarding frequency and dosing as well as combination and maintenance therapy is not well established., Methods: Ten experts experienced in research and management of cutaneous T-cell lymphomas from Germany, Austria, and Switzerland (DACH region) were asked in written form to report on indication for chlormethine gel, frequency of use, monitoring, concomitant therapies, adverse effects, combination therapies in later stages of the disease, maintenance therapy, and adherence to this therapy for mycosis fungoides. The structured answers were discussed in a consensus conference and recommendations were developed., Results: Essential for therapy with chlormethine gel is an individualized and symptom-oriented management. Because of the lack of systemic resorption of topically administered chlormethine gel, systemic adverse events are unlikely. An allergic or irritative-toxic contact dermatitis is common but manageable with adaptation of the regimen, interruption of administration, and symptom-specific supportive measurements. A step-up initial approach with application of chlormethine gel every other day is associated with a better tolerability, especially if it is alternated with topical corticosteroids., Conclusions: The use of chlormethine gel in the management of mycosis fungoides is often limited by a concomitant contact dermatitis. An adequate therapeutic regimen and the management of adverse effects can preclude an unnecessary withdrawal of therapy so that more patients can benefit from this treatment option., (© 2022 The Authors. Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft.)

Hintergrund: Chlormethin-Gel ist in Europa zur Therapie von Patienten mit Mycosis fungoides in allen Krankheitsstadien zugelassen. Die optimalen Behandlungsregime hinsichtlich Frequenz, Dosierung, Kombinations- oder Erhaltungstherapien sind noch nicht vollständig etabliert., Methodik: Zehn in der Erforschung und Behandlung kutaner T-Zell-Lymphome erfahrene Experten aus Deutschland, Österreich und der Schweiz (DACH-Region) wurden schriftlich zu Indikation, Anwendungsfrequenz, Beurteilung des Therapieerfolgs, Begleittherapie, Nebenwirkungen, Kombinationstherapien in späteren Krankheitsstadien, Erhaltungstherapie und Adhärenz im Rahmen der Therapie der Mycosis fungoides mit Chlormethin-Gel befragt. Die strukturiert aufbereiteten Ergebnisse der Umfrage wurden in einer Konsensuskonferenz diskutiert und Empfehlungen zum Management der Therapie mit Chlormethin-Gel entwickelt., Ergebnisse: Wesentlich für die Therapie mit Chlormethin-Gel ist ein individuelles, symptomorientiertes Therapiemanagement. Systemische Nebenwirkungen des Wirkstoffs sind wegen der fehlenden systemischen Verfügbarkeit bei topischer Anwendung unwahrscheinlich. Die häufig auftretende allergische oder irritativ-toxische Kontaktdermatitis kann durch eine Anpassung des Therapieregimes, Therapiepausen sowie nebenwirkungsspezifische und unterstützende Maßnahmen häufig beherrscht werden. Ein einschleichender Therapiebeginn mit Anwendung von Chlormethin-Gel jeden zweiten Tag kann die Tolerabilität wesentlich verbessern, insbesondere wenn die Therapie alternierend mit topischen Kortikosteroiden erfolgt., Schlussfolgerungen: Die Anwendung von Chlormethin-Gel bei Mycosis fungoides wird durch die begleitende Kontaktdermatitis häufig eingeschränkt. Mit einem geeigneten Therapie- und Nebenwirkungsmanagement können vermeidbare Therapieabbrüche verhindert werden und mehr Patienten von der Therapie profitieren., (© 2022 The Authors. Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft.)

Although virus-negative Merkel cell carcinoma (MCC) is characterized by a high frequency of UV-induced mutations, the expression of two viral oncoproteins is regarded as a key mechanism driving Merkel cell polyomavirus‒positive MCC. The cells in which these molecular events initiate MCC oncogenesis have yet not been identified for both MCC subsets. A considerable proportion of virus-negative MCC is found in association with squamous cell carcinoma (SCC), suggesting (i) coincidental collision, (ii) one providing a niche for the other, or (iii) one evolving from the other. Whole-exome sequencing of four combined tumors consisting of SCC in situ and Merkel cell polyomavirus‒negative MCC showed many mutations shared between SCC and MCC in all cases, indicating a common ancestry and thereby a keratinocytic origin of these MCCs. Moreover, analyses of the combined cases as well as of pure SCC and MCC suggest that RB1 inactivation in SCC facilitates MCC development and that epigenetic changes may contribute to the SCC/MCC transition., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Gemcitabine is an effective single-agent chemotherapy used in advanced stages of cutaneous T-cell lymphoma (CTCL). However, gemcitabine used in the current standard regimen is frequently associated with adverse events (AE), such as an increased risk for myelosuppression and severe infections., Objectives: We investigated in this retrospective study the effect of low-dose gemcitabine in pretreated advanced-stage CTCL and in blastic plasmacytoid dendritic cell neoplasia (BPDCN) regarding overall response (OR), progression-free survival (PFS), and AE., Material and Methods: A retrospective, multicenter study was conducted on 64 CTCL and BPDCN patients treated with gemcitabine in average absolute dosage of 1,800 mg/m2 per cycle, which is 50% lower compared to standard dosage of 3,600 mg/m2 per cycle (1,200 mg/m2 day 1, 8, 15). Evaluation of response to therapy and AE was done 4-6 weeks after the sixth cycle., Results: OR was 62% with 11% demonstrating a complete response. The median time of PFS was 12 months and median time to next treatment was 7 months. Only 3/63 patients showed serious side effects, e.g., port infection or acute renal failure. Almost 73% of the patients experienced minor to moderate side effects (CTCAE grade 0-2). Fatigue (27.2%), fever (22.7%), and mild blood count alteration (18.2%) were the most common AE., Conclusions: This retrospective analysis supports the use of low-dose gemcitabine therapy in CTCL, demonstrating with 62% OR and PFS of 12 months an almost identical response rate and survival as compared to the standard dose therapy reported in previous studies but with a significantly improved safety profile and tolerability., (© 2021 S. Karger AG, Basel.)