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Summary Background Cutaneous immune-related adverse events (irAEs) represent the most frequent toxicities induced by immune checkpoint inhibitors (ICIs). Objectives To investigate clinical associations of cutaneous toxicities induced by different ICI therapies. Methods This was a multicentre retrospective international cohort study of patients with cancer who developed cutaneous irAEs under ICI therapy. Analysis was performed of the rates and basic characteristics of all cutaneous toxicities, and identification of any associations was performed using univariate and multivariate models. Results In total, 762 patients were included, who developed 993 cutaneous toxicities. Forty different types of skin toxicities were identified. Psoriasis (175 patients, 23·0%) and pruritus (171 patients, 22·4%) were the most common toxicities, followed by macular rash (161 patients, 21·1%) and eczematous-type reactions (150 patients, 19·7%). Multivariate analysis showed that among patients with macular rash, vitiligo or multiple toxicities, patients received ICIs more frequently for melanoma than for NSCLC. Moreover, anti-CTLA4 was less frequent than anti-programmed death 1 treatment in patients with macular rash [odds ratio (OR) 0·11, 95% confidence interval (CI) 0·01–0·76] and vitiligo (OR 0·07, 95% CI 0·006–0·78). A significant association was also seen in patients treated with a combination of ICI and chemotherapy vs. ICI monotherapy. They less frequently developed psoriasis (OR 0·08, 95% CI 0·02–0·31), lichenoid reactions (OR 0·15, 95% CI 0·03–0·77) and eczematous reactions (OR 0·24, 95% CI 0·07–0·78), all compared with pruritic rash. Conclusions Our study showed that skin-oriented toxicities do not share a single pattern and are related to several factors, including the specific agent administered and the underlying malignancy treated. Follow-up plans should be individualized in order to minimize the risk for severe reactions that could compromise optimum therapeutic outcome. What is already known about this topic? Patients with cancer treated with different immune checkpoint inhibitors (ICIs) carry an increased risk of developing various types of skin toxicities. What are the clinical implications of this work? In this multicentre cohort study we showed that ICI-related skin toxicities do not share a single pattern and may depend on several factors, including the specific agent administered and the underlying malignancy.Among patients with macular rash, vitiligo or multiple skin toxicities, patients received ICIs more frequently for melanoma than for non-small cell lung cancer.The combination of ICI and chemotherapy compared with ICI monotherapy occurred to a lesser extent in patients with psoriatic rash lichenoid and eczematous reactions, compared with patients with pruritus.Clinical awareness and specialized dermatological consultation should be advocated.

Background Advanced squamous cell carcinoma (SCC) can be discriminated easily from actinic keratosis (AK) based on clinical and dermatoscopic features. However, at the initial stage of dermal invasion, SCC might still be clinically flat and discrimination from AK remains challenging, even with the addition of dermatoscopy. Objective The aim of this study was to investigate the clinical and dermatoscopic criteria that could suggest early invasion and serve as potent predictors to discriminate early SCC from AK. Methods Clinical and dermatoscopic images of histopathologically diagnosed AKs and early SCCs were evaluated for the presence of predefined criteria by 3 independent investigators. Results A total of 50 early SCCs and 45 AKs were included. The main positive dermatoscopic predictors of early SCC were dotted/glomerular vessels (odds ratio [OR] 3.83), hairpin vessels (OR 12.12), and white structureless areas (OR 3.58), whereas background erythema represented a negative SCC predictor (OR 0.22). Limitations The retrospective evaluation of images. Moreover, the differential diagnosis included in the study is restricted between AK and early SCC. Conclusions We identified potent predictors for the discrimination of AK and early SCC that may better guide management decisions in everyday clinical practice.

Background Even with the addition of dermoscopy, a significant morphologic overlap exists between irritated seborrheic keratosis (ISK) and squamous cell carcinoma (SCC). Objective The aim of this study was to investigate the dermoscopic criteria that could serve as potent predictors for the differential diagnosis between ISK and SCC. Methods Dermoscopic images of histopathologically diagnosed ISKs and SCCs were evaluated by 3 independent investigators for the presence of predefined criteria. Results A total of 104 SCCs and 61 ISKs were included. The main dermoscopic predictors of SCC were dotted vessels (odds ratio [OR], 10.4), branched linear vessels (OR, 5.30), white structureless areas (OR, 6.78), white circles surrounding follicles (OR, 23.45), a diffuse irregular (OR, 2.55) or peripheral (OR, 2.8) vessel arrangement, and a central scale arrangement (OR, 3.35). Dermoscopic predictors of ISK were hairpin vessels (OR, 0.38), a diffuse regular vessel arrangement (OR, 0.39 and OR, 0.36), and white halos surrounding vessels covering more than 10% of the lesion (OR, 0.29 and OR, 0.12). Limitations First, the retrospective design of the study; second, the differential diagnosis included in the study was restricted to ISK and SCC. Conclusions We confirmed the significant morphologic overlap between ISK and SCC, but we also identified potent predictors for the differential diagnosis between these 2 entities.

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Background: Dermoscopy is useful for the evaluation of juvenile xanthogranuloma (JXG). The classical “setting sun” pattern is characteristic of JXG, but its sensibility appears to be limited. An extensive description of other dermoscopic findings is not available in the literature. Objectives: The aim of this study was to valuate and describe the clinical and dermoscopic characteristics of a series of JXG cases. Methods: This is a retrospective descriptive study, including cases with histopathologic diagnosis of JXG, and the availability of clinical and dermoscopic images, assessed for the presence of dermoscopic features based on the available literature. Results: A total of 17 lesions were analyzed. 70.6% showed global symmetry, 35.3% presented the typical “setting sun” pattern. All lesions showed yellow-orange and/or pink-red structureless color. Other dermoscopic features were yellow globules (35.3%), shiny white streaks (23.5%), brown globules (17.6%), pale-brown network (11.8%), negative network (11.8%), erosion/ulceration (11.8%), rosettes (5.9%), and hemorrhage (5.9%). Scales were seen in 64.7% of patients. Vascular structures were observed in all the lesions, mostly in an irregular distribution (76.5%). The observed vessel types were dotted (52.9%), linear (52.9%), branching-arboriform (29.4%), comma-like (23.5%), hairpin-like (17.6%), globular (17.6%), coiled (11.8%), and milky-red globules (5.9%). Conclusions: Symmetry, yellow/orange-pink/red color, yellow globules, shiny white streaks, and irregularly distributed different types of vascular structures are the main dermoscopic features of JXG. This is the largest dermoscopic registry of JXG published to date.

Background In retrospective studies, a second primary melanoma (SPM) develops in 2%-20% of melanoma patients. Scarce evidence exists on the usefulness of total-body photography (TBP) and digital dermatoscopic documentation (DDD) for detecting SPMs. Objective The primary aim was to quantify the risk and investigate the time of occurrence of SPMs. Secondary aims were to identify risk factors for SPM and to assess the usefulness of TBP and DDD for SPM detection. Methods This prospective cohort included patients with recently diagnosed melanoma that underwent sequential clinical and dermatoscopic examinations for up to 5 years. Life table analysis and Kaplan-Meier survival analysis were performed. Multivariate Cox models were constructed to identify factors affecting the outcome. Results An SPM developed in 46 of 977 (4.7%) patients. Life table analysis revealed a 5-year cumulative risk of 8.0% for SPM. High nevus count, fair phototype, and occupational sun exposure were potent predictors of SPM. Of all new melanomas, 17.3% were diagnosed by clinical and dermatoscopic examination, 48.1% by TBP, and 34.6% by DDD. Limitations All patients followed the same protocol and diagnostic bias associated with sequential dermatoscopic imaging. Conclusion In this cohort, melanoma patients were at 8% risk of an SPM developing within 5 years. TBP and DDD significantly contributed to the early detection of SPM.

The data results of the skin cancer treatment institute aim to approach the affect of COVID-19 pandemic in the first detection of new skin cancer cases in 2020. Materials and Methods The study is retrospective and compares the data between 2020 and the expected incidence of the same year (mean of the years 2016-2019) of the new diagnosed cases of skin cancer which concerns squamous cell carcinomas (SCC), basal cell carcinomas (BCC), and melanomas. Results The results of the institutional data disclose the expected concern related to COVID-19 pandemic, with a reduction of 30.1% new skin cancer cases. The decrease of first-diagnosed SCC, BCC, and melanomas compared to expected incidence is respectively 44.8%, 22.3% and 36.3%. The mean age of the patients’ skin cancer first diagnosis is impressively lower and similarly the diagnosis at stages 0 and IA shows a same course. On the contrary, skin cancer at stages IIC, III and IV that were first detected, confirmed to be much higher. Conclusions The study data revealed that the COVID-19 pandemic effluent led to skin cancer diagnosis delay. It is highly recommended to the authorities and the national health system support the early skin cancer diagnosis of the population.

Objectives The aim of this paper is to present the experience of off-label application and possible decrease of recurrence rates in patients with ledigo maligna, when treated only with 5% imiquimod or imiquimod 5% after surgical excision in clinical narrow margins (

Background: Basal cell carcinoma can simulate melanoma and specific dermoscopic criteria have not yet been defined in a large cohort. Objective: To identify dermoscopic “trump” characteristics for differential diagnosis, identify cluster groups and assess the clinical impact of this study's findings. Methods: Retrospective, multicentric comparative study of atypical, non-facial basal cell carcinoma (≥1seven-point checklist criteria) and melanoma (with at least one BCC criteria) at dermoscopy. Observed dermoscopic features were used to develop a proposed score. Lesion clusters were defined with hierarchical analysis. Clinical impact was assessed with a blinded reader study following this study's results. Results: A total of 146 basal cell carcinoma and 76melanoma were included. Atypical vascular pattern was common to most lesions (74.5%). Twelve trump features were included in the proposed score (sensitivity 94.1% and specificity 79.5%). Cluster analysis identified 3 basal cell carcinoma and 3melanoma clusters. Findings improved overall diagnostic accuracy and confidence (26.8% and 13.8%, respectively; p&nbsp

BACKGROUND Pink skin tumours are difficult to differentiate, clinically and dermoscopically. In previous studies, mainly focused on pigmented lesions, pattern analysis provided the best sensitivity and specificity values, as compared to other algorithms. These findings suggest that the global dermoscopic appearance, based on the evaluation of prevalent features, could represent a valuable and practical approach even when dealing with pink lesions. OBJECTIVE In this study, we aimed to evaluate the diagnostic accuracy of a new dermoscopic approach for pink tumours based on the prevalent criterion, as compared to a standard diagnostic method (Menzies algorithm). METHODS The databases of two referral centres were retrospectively evaluated to retrieve dermoscopic images of amelanotic/hypomelanotic skin lesions. Two experts in dermoscopy, blinded for the final diagnosis and for clinical and demographic information, evaluated separately dermoscopic pictures of 1000 lesions according to the Menzies score and to the prevalent criterion method. RESULTS According to the high sensitivity model of the Menzies score, 129 (12.9%) lesions were considered as non-suspicious (of which 16 were false negative) and 871 (87.1%) as suspicious (of which 212 were false positive), with 97.6% sensitivity and 34.8% specificity. According to the high specificity model, 370 (37%) lesions were evaluated as non-suspicious (of which 105 were false negative) and 630 (63%) as suspicious (of which 60 were false positive), with 84.4% sensitivity and 81.5% specificity. Concerning the prevalent criterion method, 316 (31.6%) lesions were evaluated as non-suspicious (of which 46 were false negative) and 684 (68.4) as suspicious (of which 55 were false positive), with 93.2% sensitivity and 83.1% specificity. CONCLUSIONS This study demonstrated that focusing on the prevalent dermoscopic features could allow to detect malignant pink tumours with similar sensitivity but higher specificity than using the conventional Menzies scoring system.

Cancer staging is the process determining to which extent a cancer has spread and where it is located in the body. A thorough staging is of utmost importance, not only because it provides the most accurate prognostic estimation, but also because several crucial decisions, such as the treatment choice and the follow-up strategy, vary according to the tumor’s stage. The current staging system for melanoma is based on the 8(th) edition of TNM classification issued by the American Joint Committee on Cancer (AJCC) in 2017. It includes a clinical and a pathological staging, both consisting of 5 stages (0–IV). The stage of a melanoma is determined by several factors, among which the Breslow thickness, the pathological presence or absence of ulceration in the primary tumor, the presence and the number of tumor-involved regional lymph nodes, the presence or absence of in-transit, satellite and/or microsatellite metastases, and the presence of distant metastases. Following melanoma diagnosis, an accurate medical workup, in line with the stage and the physical examination, should be performed. A continuous patient monitoring is fundamental to detect a potential relapse or a second primary melanoma and should be lifelong. However, there is still no universally adopted follow-up strategy program and different follow-up schemes have been suggested. Future prospective studies are needed to evaluate different follow-up protocols according to the adopted therapy, as novel recent therapies (targeted and immunotherapies) are being increasingly used. KEY MESSAGES: Proper staging is of utmost importance because it provides accurate prognostic estimation. Several crucial decisions, such as the treatment choice and the follow up strategy, are based on the tumor stage. Physical examination during staging procedure and follow-up visits are important to avoid unnecessary imaging and laboratory tests that could increase the patients’ anxiety. A personalized approach taking into consideration the patient’s risk factors, is strongly recommended. Melanoma patients should be kept under surveillance lifelong due to an increased risk of developing a second primary melanoma and the risk of recurrence. Higher intensity follow-up strategies during the first 5 years are recommended due to higher rates of regional or distant relapse.

The indisputable contribution of dermatoscopy in early diagnosis of melanoma is widely recognized. In the last quinquennium, new data concerning specific melanoma subtypes have come to light. The dermatoscopic morphology of superficial spreading melanoma (SSM) has been extensively investigated in the literature. Atypical network, irregular dots, irregular globules, irregular streaks and irregular blotch correspond to histopathologic alterations at the level of the junction, blue-white veil and atypical vessels suggest intradermal growth, whereas regression structures, negative network and white shiny streaks might reflect junctional or dermal alterations. The list of melanoma specific criteria has been recently updated to include features that typify early melanoma, such as irregular hyperpigmented areas and prominent skin markings and features seen in melanoma on sun damaged skin such as angulated lines. Nodular melanoma lacks most of the aforementioned criteria and is typified by the coexistence of blue and black color, atypical vessels and pink color. Lentigo maligna dermatoscopic criteria mainly develop at the outline of the follicular openings. However, at an early stage these features might be very subtle and the diagnosis should be based on the exclusion of benign tumors (inverse approach). Acral lentiginous melanoma is typified by a parallel ridge pattern, but also SSM criteria should be taken into consideration. The diagnosis of subungual melanoma is based on the assessment of the color and characteristics of the pigmented nail band. For the diagnosis of mucosal melanoma, the assessment of colors is more informative than the assessment of structures and the detection of blue, white or gray should raise the suspicion of melanoma. White shiny streaks and regression structures are the most common features of desmoplastic melanoma. The diagnosis of nevoid melanoma might be highly challenging and require information on the lesion's history. Melanoma on small- and medium-sized congenital nevi is typified by an eccentric location of the suspicious area, negative network and gray angulated lines. Recent advances in knowledge on the dermatoscopic characteristics of peculiar subtypes of the tumor significantly enrich the diagnostic armamentarium of clinicians. The challenge of the forthcoming years is to better characterize biologically aggressive melanomas and to optimize the screening strategies so as to identify them.

Because of the tendency of lentigo maligna (LM) for subclinical extension, staged excisions with margin control achieve lower recurrence rates than conventional wide local excision (0-9.5% vs 8-20%). However, these surgical techniques are limited by their requirement in time, costs and training.

Background: Blue color in dermoscopy can be seen in a wide range of benign and malignant lesions, melanocytic or not. Some blue-colored dermoscopic criteria have been associated with specific tumors, such as blue-white veil with melanoma and homogeneous blue with blue nevi. However, when blue color occupies a large part of the lesion’s surface, the dermoscopic assessment might be particularly challenging. Objective: To identify dermoscopic predictors associated with benignity and malignancy in tumors characterized by a predominant dermoscopic presence of blue color. Methods: We retrospectively screened our institutional database for tumors exhibiting blue color in at least 50% of their surface with available histopathologic diagnosis. Lesions with blue color covering less than 50% of their extent and lesions not histopathologically assessed were excluded. The dermoscopic images were evaluated for the presence of predefined criteria, including the characteristics of the blue color, coexisting colors, and the vascular structures. Results: Of 91 included tumors, 53 were benign (35 blue nevi, 10 angiomas, and 8 seborrheic keratoses) and 38 malignant (12 melanomas and 26 basal cell carcinomas). Our analysis revealed 3 potent dermoscopic predictors of benignity: extension of blue color in more than 75% of the surface, diffuse distribution of blue color, and absence of vessels, posing a 2.3-fold, 5.6-fold, and 6.7-fold increased probability of benignity, respectively. In contrast, asymmetric distribution of blue color, blue clods, coexistence of gray color and linear vessels were significantly predictive of malignancy, posing a 8.9-fold, 2.8-fold, 13.5-fold, and 10.4-fold increased probability, respectively. Conclusion: In predominantly blue tumors, the probability of malignancy is high when blue color is seen in clods or is asymmetrically distributed and when gray color or linear vessels coexist. In contrast, a diffuse distribution of blue color, its expansion in more than 75% of the surface, and the absence of vessels are highly suggestive of a benign tumor.

Background: Squamous cell carcinoma of the lip accounts for 20% of all oral carcinomas. Its diagnosis may be challenging because it clinically resembles actinic cheilitis and inflammatory lesions of the lips. Objectives: To determine clinical and dermatoscopic predictors of squamous cell carcinoma of the lip vs. other lip lesions. Methods: Multicentre retrospective morphological study, including histologically confirmed cases of squamous cell carcinoma of the lip and controls consisting of actinic cheilitis and inflammatory lesions of the lips. Clinical and dermatoscopic images were evaluated for the presence of predefined criteria. Crude and adjusted odds ratios and corresponding 95% confidence intervals were calculated by univariate and multivariate logistic regression respectively. Results: A total of 177 lip lesions were evaluated, 107 (60.5%) were squamous cell carcinomas and 70 (39.5%) were controls. The most frequent dermatoscopic criteria of lip squamous cell carcinoma were scales (100%), white halos (87.3%) and ulceration (79.4%). The majority of squamous cell carcinomas displayed polymorphic vessels (60.8%), with linear (68.6%) and hairpin (67.6%) being the most frequent types. Multivariate logistic regression analysis showed that clinical predictors of lip squamous cell carcinoma were exophytic appearance and clinical hyperkeratosis, with 43-fold and 6-fold higher probability respectively. White clods and ulceration in dermoscopy presented a 6-fold and 4-fold increased risk for squamous cell carcinoma respectively. Conclusions: A scaly lesion with exophytic growth, dermatoscopically displaying white clods, ulceration and linear and hairpin vessels is very likely a squamous cell carcinoma of the lip.

Sarcoidosis and sarcoid-like reactions (SLRs) may develop in association with various malignancies, as well as in association to certain oncologic drugs, including immune checkpoint inhibitors (ICIs). We aimed to perform a narrative review with regard to the development of ICIs-associated sarcoidosis or SLRs, and to discuss the corresponding diagnostic and therapeutic challenges raised in this scenario. Apropos of a melanoma patient developing SLRs while treated with ipilimumab and nivolumab, we searched for clinically evident, ICIs-associated sarcoidosis or SLRs in the English literature. We recorded the oncologic characteristics, including type of malignancy and type of ICI, the phenotypic characteristics of sarcoidosis/SLRs, as well as the impact on immunotherapy. Including our patient, we identified 80 ICIs-associated sarcoidosis or SLRs cases. Both sexes were equally affected (40 F/40 M) and the most common malignancy was melanoma (65/80, 81.3%). Concerning the oncologic treatment, there was a predilection for pembrolizumab (23/80, 28.7%), followed by the ipilimumab/nivolumab combination (21/80, 26.3%), ipilimumab (18/80, 22.5%), nivolumab (16/80, 20.0%). Although in the majority of the cases (52/80, 65.0%) there was no need for systemic prednisolone for the management of sarcoidosis, a significant proportion of patients finally discontinued ICIs treatment (44/80, 55.0%). Phenotypically, sarcoidosis and SLRs highly imitate oncologic progression posing diagnostic difficulties. A therapeutic dilemma is also raised when there is a need for systemic prednisolone, since the latter may jeopardize the therapeutic efficacy of immunotherapy. Sarcoidosis and SLRs, though rare, can present in oncologic patients treated with ICIs. Clinicians should be aware of this possibility and the related diagnostic and therapeutic challenges they have to face in this scenario.

Basal cell carcinoma (BCC) is the most common skin cancer in white skin individuals. The treatment of choice is surgical excision, but several other therapeutic choices are available and might also be efficient and cost-effective in selected cases of low-risk BCC or when surgery is complicate or contraindicated. The aim of the current study was to analyze the applied treatments for BCC in the real-life practice of a tertiary hospital, and investigate factors associated to the tumor and the patients that might influence the treatment selection of clinicians. Data on all BCCs treated from 1st January 2018 to 31st December 2019 were extracted. A total of 751 BCCs from 585 patients were included. The baseline characteristics of patients and tumors, the type of applied treatment and the histopathologic report when available were analyzed. Most tumors were located on the head/neck (64.2%). The most frequently applied treatment was surgical excision (580/751, 77.2%). In 22.8% of tumors a nonsurgical treatment was selected. The most frequently selected alternative treatments were, imiquimod, cryosurgery, their combination (immunocryosurgery), and vismodegib. A pretreatment diagnosis of superficial BCC was associated with a 12-fold increased probability of selecting a nonsurgical treatment except of vismodegib. Every added year of age increased the probability of selecting a nonsurgical treatment by 3-fold. Every added mm of diameter increased the possibility of vismodegib use by 4%. Surgery is the most frequently applied BCC treatment, but nonsurgical modalities do also have an essential role in real settings.

Immune checkpoint inhibitors (CPIs) are targeted molecules that modulate the immune system, assist with self-tolerance, and minimize collateral tissue damage when immune responses are activated. Although they are characterized by a favorable risk/benefit ratio, immune checkpoint blockade has been associated with a new subset of autoimmune-like toxicities, named immune-related adverse events (irAE). Dermatologic reactions are among the most prevalent irAE triggered by CPIs. In a majority of cases they are self-limiting and readily manageable. However, it is not uncommon that they result in severe skin involvement and impairment of patients’ quality of life. Awareness of the spectrum of cutaneous irAEs is mandatory for every clinician involved in the management of oncologic patients. The role of the dermatologists is essential because early recognition and appropriate management of skin toxicity may prevent dose modifications and discontinuation of CPIs. The latter is particularly relevant, considering that recent data suggest favorable oncologic response in patients developing irAEs.

Background The dermoscopic features of superficial basal cell carcinoma (sBCC) and Bowen's disease (BD) have been extensively investigated, and dermoscopy was shown to significantly improve their recognition. However, incorrectly diagnosed cases still exist, with a considerable number of sBCCs dermoscopically interpreted as BD. Our aim was to investigate the dermoscopic variability in sBCC and BD on different anatomic sites, to identify potent dermoscopic predictors for each diagnosis and to investigate the potential source of the inaccurate clinico-dermoscopic diagnosis of some sBCCs. Methods Dermoscopic images of histopathologically diagnosed sBCC and BD were evaluated by three independent investigators for the presence of predefined criteria. Subsequently, three independent investigators with expertise in dermoscopy classified the tumours as sBCC or BD based on the dermoscopic image. Diagnostic accuracy scores were calculated and crude and adjusted odds ratios, and 95% confidence intervals were calculated by univariate and conditional multivariate logistic regression, respectively. Results A total of 283 lesions were included in the study (194 sBCCs and 89 BD). The main dermoscopic predictors of BD were dotted vessels (7.5-fold) and glomerular vessels (12.7-fold). The presence of leaf-like areas/spoke-wheel areas/concentric structures (OR = 0.027) and arborizing vessels (OR = 0.065) has predicted sBCC. Multivariate risk factors for sBCC misclassification were the location on lower extremities (OR = 5.5), the presence of dotted vessels (OR = 59.5) and the presence of large ulceration (OR = 6.4). In contrast, the presence of brown-coloured pigmentation was a protective predictor for misdiagnosis (OR = 0.007). Finally, a subgroup analysis of lesions located on lower extremities revealed two additional potent predictors of sBCC: superficial fine telangiectasia (SFT) and whity shiny blotches/strands. Conclusions Dotted and glomerular vessels are strong predictors of BD. When located on the lower extremities, sBCC may also display dotted vessels, rendering its recognition problematic. On the latter anatomic site, clinicians should consider SFT and whity shiny blotches/strands as additional sBCC predictors.

Dermoscopy has been documented to increase the diagnostic accuracy of clinicians evaluating skin tumours, improving their ability to detect skin cancer and better recognize benign moles. However, dermoscopically 'false-positive' and 'false-negative' tumours do exist. False-positive diagnosis usually leads to unnecessary excisions. False-negative diagnosis is much more dangerous, as it might result in overlooking a cancer, with severe undesirable consequences for the patient and the physician. Therefore, management strategies should mainly focus on addressing the risk of dermoscopically false-negative tumours. The most frequent benign tumours that might acquire dermatoscopic characteristics suggestive of malignancy are seborrhoeic keratosis (SK), including solar lentigo, melanoacanthoma, irritated, clonal and regressive SK, angioma (mainly thrombosed angioma and angiokeratoma), dermatofibroma, benign adnexal tumours and naevi (Clark, Spitz, recurrent, combined, sclerosing). The most useful clues to recognize these tumours are the following: solar lentigo - broad network; melanoacanthoma - sharp border; irritated SK - regularly distributed white perivascular halos; clonal SK - classic SK criteria; regressive SK - remnants of SK; targetoid haemosiderotic haemangioma - dark centre and reddish periphery; thrombosed angioma - sharp demarcation; angiokeratoma - dark lacunae; atypical dermatofibromas - palpation; follicular tumours - white colour; sebaceous tumours - yellow colour; Clark naevi - clinical context; Spitz/Reed naevi - age; combined naevi - blue central area; recurrent naevi - pigmentation within the scar; sclerosing naevi - age and location on the upper back; blue naevi - history. Malignant tumours that might mimic benign ones and escape detection are melanoma (in situ, nevoid, spitzoid, verrucous, regressive, amelanotic), squamous cell carcinoma (mainly well-differentiated variants) and rarely basal cell carcinoma (non-pigmented variants). The most useful clues to recognize the peculiar melanoma subtypes are as follows: melanoma in situ - irregular hyperpigmented areas; nevoid melanoma - history of growth; spitzoid melanoma - age; verrucous melanoma - blue-black sign; regressive melanoma - peppering or scar-like depigmentation; amelanotic melanoma - pink colour, linear irregular vessels, dotted vessels. In this article, we summarized the most frequent dermoscopic variations of common skin tumours that are often misinterpreted, aiming to assist clinicians to reduce the number of false diagnoses.

Over the last few years, several articles on dermoscopy of non-neoplastic dermatoses have been published, yet there is poor consistency in the terminology among different studies.We aimed to standardize the dermoscopic terminology and identify basic parameters to evaluate in non-neoplastic dermatoses through an expert consensus.The modified Delphi method was followed, with two phases: (i) identification of a list of possible items based on a systematic literature review and (ii) selection of parameters by a panel of experts through a three-step iterative procedure (blinded e-mail interaction in rounds 1 and 3 and a face-to-face meeting in round 2). Initial panellists were recruited via e-mail from all over the world based on their expertise on dermoscopy of non-neoplastic dermatoses.Twenty-four international experts took part in all rounds of the consensus and 13 further international participants were also involved in round 2. Five standardized basic parameters were identified: (i) vessels (including morphology and distribution); (ii) scales (including colour and distribution); (iii) follicular findings; (iv) 'other structures' (including colour and morphology); and (v) 'specific clues'. For each of them, possible variables were selected, with a total of 31 different subitems reaching agreement at the end of the consensus (all of the 29 proposed initially plus two more added in the course of the consensus procedure).This expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This tool, if adopted by clinicians and researchers in this field, is likely to enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology. What's already known about this topic? Over the last few years, several papers have been published attempting to describe the dermoscopic features of non-neoplastic dermatoses, yet there is poor consistency in the terminology among different studies. What does this study add? The present expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This consensus should enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology.

Background: Thin nodular melanoma (NM) often lacks conspicuous melanoma-specific dermatoscopic criteria and escapes clinical detection until it progresses to a thicker and more advanced tumour. Objective: To investigate the dermatoscopic morphology of thin (≤2mm Breslow thickness) vs. thick (>2mm) NM and to identify dermatoscopic predictors of its differential diagnosis from other nodular tumours. Methods: Retrospective, morphological case–control study, conducted on behalf of the International Dermoscopy Society. Dermatoscopic images of NM and other nodular tumours from 19 skin cancer centres worldwide were collected and analysed. Results: Overall, 254 tumours were collected (69 NM of Breslow thickness ≤2mm, 96 NM >2mm and 89 non-melanoma nodular lesions). Light brown coloration (50.7%) and irregular brown dots/globules (42.0%) were most frequently observed in ≤2mm NMs. Multivariate analysis revealed that dotted vessels (3.4-fold), white shiny streaks (2.9-fold) and irregular blue structureless area (2.4-fold) were predictors for thinner NM compared to non-melanoma nodular tumours. Overall, irregular blue structureless area (3.4-fold), dotted vessels (4.6-fold) and serpentine vessels (1.9-fold) were predictors of all NM compared to non-melanoma nodular lesions. Limitations: Absence of a centralized, consensus pathology review and cases selected form tertiary centres maybe not reflecting the broader community. Conclusions: Our study sheds light into the dermatoscopic morphology of thin NM in comparison to thicker NM and could provide useful clues for its differential diagnosis from other non-melanoma nodular tumours.