This evidence- and consensus-based guideline for the treatment of acne was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. This guideline is an update of the 2016 version. This is a short summary of the full version of the EuroGuiDerm Evidence-based Guideline for the Treatment of Acne. For the complete guideline text, detailed methods report, and comprehensive evidence report, please refer to the online full version. In this targeted update, the guideline group prioritized three key clinical questions considered most relevant for current practice: (a) For which types of acne and patient groups should isotretinoin be recommended versus systemic antibiotics, and with what strength of recommendation? (b) What is the appropriate duration for systemic antibiotic therapy? For which types of acne and patient groups should hormonal treatments and spironolactone be recommended, and with what strength of recommendation? For which types of acne and patient groups should new topical treatments, including trifarotene and clascoterone, be recommended and with what strength of recommendation? Additionally, the updated guideline provides revised recommendations regarding: safety of benzoyl peroxide (BPO), selection of systemic antibiotic therapy, treatment considerations during pregnancy, isotretinoin dosing strategies, and the use of hormonal antiandrogenic contraceptives or other combined hormonal contraceptives, as well as spironolactone. All other aspects remain unchanged from the 2016 guideline.

The role of diet and nutrition in acne pathogenesis has long been debated. Acne patients consistently report interest in how food may influence their disease, and observational studies have highlighted associations with high glycaemic load diets, skim/low-fat milk, whey protein supplements and an unbalanced omega-6/omega-3 fatty acid (FA) ratio. In this review, we discuss the potential role of diet on acne pathogenesis, including dairy, omega-3 FAs, low glycaemic load diet, vegan and Mediterranean diet. We present a comprehensive in-depth review of studies on diet in acne, provide insight into mechanistic pathways and share practical counselling strategies. There is a small number of controlled studies on dietary interventions for acne patients that are further hindered by the difficulty of controlling the various food components in everyday diets and the effect of body weight reduction with low glycaemic diets. According to current guidelines, further interventional studies are warranted to provide robust results on whether specific dietary modifications may be advised to acne patients. Although larger controlled trials are still needed, dermatologists can already provide relevant dietary information especially with the aim of balanced nutrition and healthy body weight while avoiding restrictive or potentially harmful regimens.

Neoadjuvant treatment for skin cancer refers to treatment given to resectable tumors before surgery with the primary aim of improving prognostic outcomes. In addition, it may downstage the tumor to decrease surgical morbidity, and may de-escalate adjuvant therapies in cases of complete response. This in-depth review discusses the principles of neoadjuvant immunotherapy for cutaneous melanoma and invasive cutaneous squamous cell carcinoma (CSCC). Lessons learned from prospective neoadjuvant systemic immunotherapy clinical trials in melanoma are explored, available evidence from research studies for resectable CSCC is detailed, and key studies are illustrated in schematic figures. Outcomes and limitations of current evidence are presented and practical considerations are highlighted, including the risks of immune-related adverse events and the need for biomarkers to identify patients most likely to benefit. Implications are illustrated for response-adapted treatment de-escalation protocols, and trials are indicated that could inform future standards of care. While clinical trials on neoadjuvant immunotherapy and dual checkpoint blockade strategies for melanoma is a rapidly growing field, the small number of clinical trials in CSCC highlights the need to design and perform clinical trials for patients with CSCC in order to be able to provide for them treatments based on high standards of research.

The MITF E318K variant has been associated with melanoma risk, while risk associated with other variants or of other cancers remains uncertain. We performed a systematic review with meta-analysis of 11 retrospective case–control studies to evaluate cancer risks associated with germline MITF variants. Across 8,606 melanoma patients and 17,953 controls, the E318K variant was detected in 2.1% and 0.8% of individuals, respectively, corresponding to a significantly increased melanoma risk (OR 2.55, 95% CI 1.90–3.43). The association was stronger in patients with multiple primary melanomas, with carrier frequencies up to 2.6% compared to 1.0% in single melanoma cases and ORs reaching 4.45 in individual studies. Phenotypic analyses showed enrichment of high nevus burden (> 200 nevi), with ORs up to 12.4 in multiple melanoma cohorts. No consistent association with age at onset or pigmentary traits was observed. Evidence for non-melanoma cancers was limited and heterogeneous: a single study reported increased renal cancer risk (OR 7.64), whereas larger cohorts failed to replicate this finding; an association with pheochromocytoma/paraganglioma was observed (OR 3.19) but lacks confirmation. No other MITF variants demonstrated significant cancer risk. These findings support MITF E318K as a moderate-penetrance melanoma susceptibility allele, particularly associated with multiple primary melanomas.

Nevus counts in the divergent pathway model of melanoma development have been studied mainly in patients in Australia. Our aim was to compare nevus counts and the melanoma subtype for melanomas arising on chronically sun-exposed body versus non-chronically sun-exposed body locations in Southern European patients. This was a retrospective study of prospectively collected data from 2013 to 2023 at a melanoma referral center in Athens, Greece, in patients diagnosed with invasive melanoma of the superficial spreading melanoma (SSM) or nodular melanoma subtype. Multivariate multinomial logistic regression analysis was performed. In 1252 patients with SSM or nodular melanoma, the median age (interquartile range) was 57 (46, 67) years old and 51% were males. Regarding nevus counts, 57.9% of patients had 0-25 nevi (low), while the remaining 42.1% had greater than 25 nevi (high). In multivariate analysis, those with greater than 25 nevi (versus ≤25) were significantly less likely to have melanoma developing on the head/neck (chronically sun exposed body site) [odds ratio (OR): 0.60, 95% confidence interval (CI): 0.38-0.93] or on the lower extremity (OR: 0.63, 95% CI: 0.44--0.87), compared with having melanoma on the trunk (non-chronically sun exposed). Regarding the melanoma subtype, those with SSM versus nodular melanoma subtype were 53% less likely to have melanoma developing on the head/neck (OR: 0.47, 95% CI: 0.30-0.75), compared with the trunk. The melanoma subtype (SSM or nodular melanoma) did not significantly differ across upper extremity (OR: 0.94, 95% CI: 0.59-1.51) or lower extremity (OR: 1.03, 95% CI: 0.66-1.62) locations of melanoma development compared with the trunk. In conclusion, the association of higher nevus counts with melanomas developing on the trunk supports the divergent pathways of melanoma development in Southern European patients. Melanomas on the head/neck were significantly associated with lower numbers of nevi and were more likely to be nodular melanoma subtype.

Invasive cutaneous squamous cell carcinoma (CSCC) is one of the most common cancers in white populations, accounting for 20% of all cutaneous malignancies. A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF), the European Society for Radiotherapy and Oncology (ESTRO), the European Union of Medical Specialists (UEMS)-Dermatology Venereology, and the European Organization of Research and Treatment of Cancer (EORTC), was formed to update guideline recommendations on CSCC (previous version 2023), based on current literature and expert consensus. Part 1 of the guidelines addresses diagnostics and prevention in immunocompetent as well as immunosuppressed patients. CSCC may be classified as easy-to-treat (vast majority) or difficult-to-treat, common primary CSCC, and is further defined as low risk or higher risk depending on the risk of recurrence or metastasis. A new classification of five groups of difficult-to-treat CSCC (DTT-CSCC) is proposed, published in 2025 by EADO experts and reflecting the commonly encountered clinical challenges. Difficult-to-treat (DTT) CSCC includes DTT-common CSCC groups 1 and 2 (which correspond to a subgroup of common CSCC that are complex to treat due to tumor and/or patient characteristics or multiplicity), DTT-CSCC group 3 corresponding to locally advanced CSCC, and DTT-CSCC groups 4 and 5 corresponding to CSCC with locoregional or distant metastases, respectively. The first step of diagnostics is based on clinical and dermatoscopic features, and is always confirmed by histopathology. The presence of risk factors characterizes higher risk CSCC, and the more risk factors, the higher the risk. After the histological diagnosis of CSCC has been established, the second step includes staging procedures, such as physical examination and, when indicated, imaging. In the third and final step, the clinical, histologic and radiologic findings are incorporated into staging systems. The more widely used staging systems are the American Joint Committee on Cancer 8th edition (AJCC8) and the Brigham and Women’s Hospital (BWH) systems. Prevention strategies include oral nicotinamide and sun protection measures.

Part 2 of the guideline addresses the updates on treatment recommendations in immunocompetent as well as immunosuppressed patients with invasive cutaneous squamous cell carcinoma (CSCC), based on current literature and expert consensus. A multidisciplinary panel of experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF), the European Society for Radiotherapy and Oncology (ESTRO), the European Union of Medical Specialists (UEMS)-Dermatology Venereology and the European Organization of Research and Treatment of Cancer (EORTC), was formed to update the previous guideline on CSCC (version 2023). For common primary CSCC, first-line treatment is surgical excision with post-operative margin assessment or micrographically controlled surgery. Achieving clear histological margins is key for patients with CSCC amenable to surgery. Radiotherapy should be considered for non-surgical candidates/tumors. For patients with macroscopic regional lymph node metastases, individualized treatment should be discussed in the multidisciplinary tumor board. For patients with metastatic or locally advanced CSCC who are not candidates for curative surgery or radiotherapy, anti-PD-1 agents are the first-line systemic treatment, with cemiplimab being the approved systemic agent for advanced CSCC by the EMA. Second-line systemic treatments for advanced CSCC, include clinical trials, EGFR inhibitors (cetuximab) combined with anti-PD-1 immunotherapy, or chemotherapy or radiotherapy. The decision for adjuvant cemiplimab for CSCC at high risk of recurrence after surgery and radiotherapy should be discussed in the multidisciplinary tumor board. In addition, multidisciplinary board decisions are mandatory for all patients with advanced CSCC, considering the risks of toxicity, the age and frailty of patients and co-morbidities, including immunosuppression. Patients should be engaged in informed, shared decision-making on management and be provided with best supportive care to improve symptom management and quality of life. Frequency of follow-up visits and investigations for subsequent new CSCC depend on underlying risk characteristics.

Vitamin A and analogs are widely used in dermatology, with retinoids being natural and synthetic vitamin A derivatives. Topical retinoids (especially tretinoin and tretinoin precursors) can diminish photoaging and contribute to the thickening and restoration of skin collagen. Retinoids used as therapeutic agents include oral retinoids (eg, isotretinoin, acitretin, alitretinoin, and bexarotene) and topical retinoids (eg, isotretinoin, tretinoin, adapalene, tazarotene, and trifarotene). Although retinoids have traditionally been used for skin disorders of keratinization, such as psoriasis, pityriasis rubra pilaris, Darier disease, and ichthyoses, there is a variety of indications of retinoids for the treatment of skin diseases, including diseases of the pilosebaceous unit such as acne vulgaris, pigmentary disorders such as melasma, or cutaneous malignancies such as cutaneous T-cell lymphoma. Other retinoids with distinct routes of administration (oral or topical) and distinct dosing or safety profiles are recommended for different skin disorders. We discuss the mode of action and indications of retinoids used as pharmacologic agents in dermatology and provide an update on their use, effectiveness, and tolerability.

Die Evidenzlage zur Unterstützung einer zweizeitigen weiten lokalen Exzision (WLE) mit einem Sicherheitsabstand von 5 mm bei Melanomata in situ (MIS) vom Typ Nicht‐Lentigo‐maligna (Nicht‐LM) im Vergleich zu schmaleren Resektionsrändern ist unklar. Ziel dieser Übersichtsarbeit war der Vergleich der Häufigkeit von Lokalrezidiven (LR) mit unterschiedlichen Sicherheitsabständen nach der vollständigen chirurgischen Exzision (R0) von Nicht‐LM‐MIS. Wir führten eine systematische Literatursuche in PubMed, Scopus und der Cochrane Library bis zum 17. März 2024 durch. Es wurde die PRISMA‐Checkliste verwendet. Von den 3047 gefundenen Artikeln wurden sieben retrospektive Studien mit insgesamt 1526 Fällen von Nicht‐LM‐MIS sowie Exzisionen mit freien Sicherheitsabständen nach WLE (6 Studien) oder Mohs mikrografischer Chirurgie (1 Studie) eingeschlossen. Die meisten Nicht‐LM‐MIS befanden sich am Rumpf oder an den Extremitäten (68%–100%). In vier Studien wurden schmalere Abstände verwendet, die von keiner WLE bis zu 4 mm reichten, mit nur einem LR‐Ereignis. In den verbleibenden drei Studien wurden Standard‐ oder breitere Abstände verwendet und nur zwei LR gemeldet. Die mediane Nachbeobachtungszeit reichte von 48 Monaten bis zu 6,6 Jahren. Die Gesamtgewissheit und Evidenzqualität waren sehr gering. Die Ergebnisse unserer systematischen Übersicht zeigen, dass es für die Empfehlung in den aktuellen Leitlinien, bei Nicht‐LM‐MIS eine Nachexzision bei initial freien Rändern durchzuführen, keine überzeugende Evidenz gibt.

BACKGROUND:There is limited data on the association of height, age, and sex with total body nevus counts. METHODS:We performed a single-center, university hospital-based study in adults without previous history of melanoma who underwent total body skin examination for screening of nevi. Multivariable logistic regression models were used for the association between per 10 cm increments in height and the outcome of the total body nevus counts, after adjustment for age, sex, and skin color. RESULTS:In 813 individuals with a median age of 43 years, nevus counts were lower in older individuals in multivariable analysis. Those older than 51 years had 73% lower likelihood to have 30-60 nevi (odds ratio [OR] vs. < 15 nevi: 0.27, 95% confidence interval [CI]: 0.14-0.55), and 60% lower likelihood to have more than 60 nevi (OR: 0.40, 95% CI: 0.20-0.81). Each 10 cm increase of height did not have a significant independent association with greater nevus counts overall. In age-stratified analysis, in individuals 50 years old or younger, each 10 cm increase of height was not associated with having 30 or more nevi (OR: 1.03, 95% CI: 0.79-1.33). In individuals older than 50 years old, each 10 cm increase of height was significantly associated with lower likelihood of having 30 or more nevi (OR: 0.57, 95% CI: 0.33-0.998, p = 0.049). CONCLUSION:Our study showed lower nevus counts in older individuals and that the age-related lower nevus counts were more pronounced in those who are taller, suggesting possible underlying common drivers for height and age-related nevi involution mechanisms.

BACKGROUND:There is limited data on the public awareness that melanoma can have a small size. METHODS:We performed a single-center, university hospital-based survey study in individuals who were screened for melanocytic nevi with total body skin photography and digital dermoscopy, to investigate the awareness that melanoma may be small and knowledge of the ABCDE rule. RESULTS:In 547 individuals, the median age was 43 years, and 49.5% were females. The change (in color, shape, or size) in "a mole smaller than a pencil eraser" would be a sign of worry for 57.7% of participants. The appearance of a "new mole" would be a sign of worry for only 43.7%. Regarding reasons to visit a doctor, 54.7%, 65.7%, and 61.4% responded that they would worry about a weird mole of small, medium or large size, respectively. Approximately half of respondents (59.7%) were aware that melanoma can have a small size. Only a third of respondents (32.3%) answered that they had heard of the ABCD rule for melanoma. In multivariable logistic regression analysis, being aware that melanoma can have a small size was not associated with age or sex, while it was significantly associated with the number of digital dermoscopy visits (odds ratio [OR]: 1.62, 95% confidence interval [CI]: 1.12-2.33). CONCLUSIONS:Our study showed low awareness that melanoma can be small in size and of the ABCDE rule for the detection of melanoma. Identifying gaps in knowledge about melanoma may guide the design of clear, targeted messages to educate the public and enhance early self-detection.

The strength of evidence supporting a 2-step wide local excision (WLE) with 5 mm safety margins for melanoma in situ non-lentigo maligna (non-LM) type, compared with narrower margins, is unclear. This review aims to compare the frequency of local recurrence (LR) with different safety margins, after the complete surgical excision (R0) of non-LM MIS. We performed a systematic literature search in PubMed, Scopus, and the Cochrane Library up to March 17, 2024. The PRISMA checklist was used. Of 3,047 articles retrieved, seven retrospective studies were included, enrolling a total of 1,526 non-LM MIS cases excised with clear safety margins, after WLE (6 studies) or Mohs surgery (1 study). Most non-LM MIS were located on the trunk/extremities (68%-100%). Narrower margins were used in four studies, ranging from no WLE to 4 mm, and there was only one LR. Standard or wider margins were used in the remaining three studies reporting only two LR. The median follow-up ranged from 48 months to 6.6 years. The overall certainty and quality of evidence were very low. These findings of our systematic review highlight that current guidelines recommending the re-excision for non-LM MIS with clear initial margins lack strong evidence in support of this practice.

This review, focusing on cutaneous adnexal carcinomas, extramammary Paget disease (EMPD), cutaneous angiosarcomas (cAS) and Kaposi sarcoma (KS), summarizes their local recurrence and metastasis rates, tumor mutation burden (TMB), PD-L1 expression, and off-label treatment with systemic anti-PD-1 agents. PD-L1 expression and tumor mutation burden (TMB) were highly variable in adnexal carcinomas (also depending on the histological subtype), cAS and KS tumors, and some responses were noted even in lack of PD-L1 expression or in low-TMB tumors. There were encouraging best overall responses in patients with advanced rare skin carcinomas treated with anti-PD-1 agents in the literature, mostly after failure of other systemic treatments. We identified a total of 3 patients with sebaceous carcinoma (2 with complete response [CR], 1 with partial response [PR]), 5 with porocarcinoma (3 CR, 1 PR, 1 progression of disease [PD]), 2 with spiradenocarcinoma (1 PR, 1 PD), 1 with trichilemmal carcinoma with PR, 9 with EMPD (1 CR, 5 PR, 3 PD), 32 with cAS (5 CR, 18 PR, 9 PD), and 92 with KS (5 CR, 53 PR, 23 SD, 11 PD). However, a large variety of anti-PD-1 agents were used, in monotherapy or in combination with other systemic therapy, in a relatively small number of patients, limiting interpretations on their individual efficacy. The development of clinical guidelines on rare skin carcinomas may provide standardized guidance to physicians towards best care.

Importance The overdiagnosis of melanoma in situ (MIS) is well documented. There is limited evidence on the rate of local recurrence of the non-lentigo maligna (non-LM)/non-acral lentiginous melanoma (non-ALM) subtypes. Objective To investigate local recurrence and prognosis in non-LM/non-ALM MIS, the histopathological clearance of the excisional biopsy margins, and the association with the size of wide excision margins. Design, Setting, and Participants This retrospective cohort study included patients with non-LM/non-ALM MIS diagnosed from 1991 to 2023 who were followed up for at least 1 year at the Skin Cancer and Melanoma Unit of Andreas Sygros University Hospital in Athens, Greece. Patients with a history of invasive melanoma or a histopathological diagnosis of LM or ALM in situ were excluded. Median (IQR) follow-up was 5.2 (2.9-7.9) years. Deidentified data on patient demographics and clinical characteristics, including the histopathological clearance of margins of the initial excisional biopsy and the size of margins of the wide excision, were obtained from medical records. Main Outcomes and Measures The primary outcomes were local recurrence, metastasis, and melanoma-specific survival. Results A total of 401 patients (214 [53.4%] women) with 403 non-LM/non-ALM MIS and a median (IQR) age of 52 (40-62) years were included in the analysis. MIS was frequently located on the trunk (201 lesions [49.9%]), followed by the lower extremity (99 [24.6%]), the upper extremity (71 [17.6%]), and the head and neck (32 [7.9%]). All lesions were initially treated with excisional biopsy, followed by wide excision for 372 (92.3%). There was only 1 local recurrence in a patient with involved margins at the excisional biopsy who did not undergo wide excision and developed an invasive melanoma 14 months later. Thirty lesions in 30 patients had clear excisional biopsy margins with no wide excision and had no recurrence at a median (IQR) follow-up of 8.1 (4.1-12.9) years. In 23 patients with 23 lesions that had wide excision with narrower than the standard 0.5-cm margins (mean [SD] margin size, 0.36 [0.07] cm), no recurrences were found at a median (IQR) follow-up of 4.3 (2.7-6.2) years. During follow-up, 6 patients (1.5%) developed a lesion suspicious for recurrence near the excision scar, which was excised and showed nevus or solar lentigo on histopathology. No patients had metastasis or melanoma-specific death. Conclusions and Relevance This cohort study found that diagnostic excisional biopsies with clear margins may be sufficient for treating MIS; however, larger studies are necessary.

INTRODUCTION:The frequency and type of nevus association in histology in melanoma in situ (MIS) is unclear. METHODS:We performed a retrospective study to investigate the characteristics, frequency, and type of adjacent nevus in histology (common or dysplastic) in MIS. Lentigo maligna (LM) and in situ acral lentiginous melanomas (ALMs) were excluded. RESULTS:From 1991 to 2023, there were 448 available non-LM/non-ALM MIS. MIS was nevus associated (NAM-MIS) in 353 cases (79%). Of these cases, 326 NAM-MIS cases (94%) had dysplastic nevus remnants. Among the dysplastic nevus MIS, 176 (54%) were adjacent with severely dysplastic nevus. Nevus-associated MIS versus de novo MIS was more frequently located on the trunk (54% vs. 36%) and less frequently located on the head/neck (8% vs. 11%) (p = 0.02). CONCLUSIONS:Nevus association is a common finding in MIS and almost all nevus-associated MIS was associated with a dysplastic nevus. These findings may indicate an evolution from severely dysplastic nevus to MIS and also reflect the equivalent histopathological classification and support their previously proposed biological equivalence as not obligate precursors of invasive melanomas.