[Digital and innovative teaching in dermatology : Practically oriented teaching online]. / Digitale und innovative Lehre in der Dermatologie : Praktisch orientierte Lehre online.

BACKGROUND: Due to the corona pandemic and also to the new competence-oriented catalogue of learning objectives in medicine and the master plan for medical studies 2020, the development of digital and practical teaching concepts has experienced a great increase in importance. AIM OF THE WORK: As a result of this development, it was an important task to establish this combination and incorporate it into the curricular teaching process. MATERIAL AND METHODS: The "Toolkit dermatology" was established, which was sent to a total of more than 650 students at German university dermatology clinics. Using educational films, the students were able to practice their skills. In a further development, the toolkit was combined with classroom lectures and the students were asked to evaluate the toolkit online. RESULTS: The vast majority of students (95-100%) clearly stated that the toolkit helped them to develop their practical skills. Some of them were in fact motivated to complete a clinical traineeship/practical tertial year in dermatology (21-88%). The combination of toolkit and subsequent classroom teaching was also rated very positively (82.2%), as this hybrid mode of teaching provided a better understanding. DISCUSSION: Digital teaching formats as part of the concept of blended learning, i.e. the combination of virtual and analogue teaching formats, are becoming increasingly more important. Solutions for the disadvantages, such as the lack of real interaction and suitable examination formats, still remain to be found; however, the toolkit project demonstrates that hands-on and digital teaching can lead to high student motivation as well as a high educational standard.

2021 international consensus statement on optical coherence tomography for basal cell carcinoma: image characteristics, terminology and educational needs.

BACKGROUND: Despite the widespread use of optical coherence tomography (OCT) for imaging of keratinocyte carcinoma, we lack an expert consensus on the characteristic OCT features of basal cell carcinoma (BCC), an internationally vetted set of OCT terms to describe various BCC subtypes, and an educational needs assessment. OBJECTIVES: To identify relevant BCC features in OCT images, propose terminology based on inputs from an expert panel and identify content for a BCC-specific curriculum for OCT trainees. METHODS: Over three rounds, we conducted a Delphi consensus study on BCC features and terminology between March and September 2020. In the first round, experts were asked to propose BCC subtypes discriminable by OCT, provide OCT image features for each proposed BCC subtypes and suggest content for a BCC-specific OCT training curriculum. If agreement on a BCC-OCT feature exceeded 67%, the feature was accepted and included in a final review. In the second round, experts had to re-evaluate features with less than 67% agreement and rank the ten most relevant BCC OCT image features for superficial BCC, nodular BCC and infiltrative and morpheaphorm BCC subtypes. In the final round, experts received the OCT-BCC consensus list for a final review, comments and confirmation. RESULTS: The Delphi included six key opinion leaders and 22 experts. Consensus was found on terminology for three OCT BCC image features: (i) hyporeflective areas, (ii) hyperreflective areas and (iii) ovoid structures. Further, the participants ranked the ten most relevant image features for nodular, superficial, infiltrative and morpheaform BCC. The target group and the key components for a curriculum for OCT imaging of BCC have been defined. CONCLUSION: We have established a set of OCT image features for BCC and preferred terminology. A comprehensive curriculum based on the expert suggestions will help implement OCT imaging of BCC in clinical and research settings.

[Confocal line-field OCT]. / Konfokale Line-Field-OCT.

Optical coherence tomography (OCT) and confocal laser microscopy (CLSM) are established non-invasive methods in clinical dermatological routine diagnosis. Whereas CLSM is especially useful to distinguish between nevi and melanoma, OCT is suitable for the diagnosis and differentiation of non-melanoma skin cancer. Line-field confocal optical coherence tomography (LC-OCT) is a new innovative device, which has better cellular resolution than OCT and a higher penetration depth than CLSM. Similar to CLSM, LC-OCT also allows 3D images in real time to be taken. Therefore LC-OCT is very useful for the examination of skin lesions of all kinds, since it unites the features of CLSM and OCT.

Line-field confocal optical coherence tomography for the in vivo real-time diagnosis of different stages of keratinocyte skin cancer: a preliminary study.

BACKGROUND: The treatment of keratinocyte cancers (KC) strictly depends on their differentiation and invasiveness. Non-invasive diagnostic techniques can support the diagnosis in real time, avoiding unnecessary biopsies. This study aimed to preliminarily define main imaging criteria and histological correlations of actinic keratosis (AK), Bowen's disease (BD) and squamous cell carcinoma (SCC) using the novel device line-field confocal optical coherence tomography (LC-OCT). METHODS: Dermoscopy and LC-OCT images of 73 histopathologically confirmed lesions (46 AKs, 11 BD and 16 SCCs) were included in the study. Exemplary lesions (10 AKs, 5 BD and 5 SCCs) were additionally investigated with optical coherence tomography and reflectance confocal microscopy. RESULTS: Most common LC-OCT findings of KC in the descriptive statistics were hyperkeratosis/parakeratosis, disruption of stratum corneum, broadened epidermis, basal and suprabasal keratinocyte atypia, dilated vessels/neoangiogenesis and elastosis/collagen alterations. In the univariate multinomial logistic regression, a preserved DEJ was less common in SCC compared with AK and BD, BD displayed marked keratinocyte atypia involving all epidermal layers (bowenoid pattern), while SCC showed ulceration, increased epidermal thickness, keratin plugs, acantholysis, not visible/interrupted DEJ and epidermal bright particles. LC-OCT increased the diagnostic confidence by 24.7% compared with dermoscopy alone. CONCLUSIONS: Our study describes for the first time specific LC-OCT features of different stages of KC and their histopathological correlates, focusing on keratinocyte morphology and architecture of the epidermis and DEJ. LC-OCT may open new scenarios in the bedside diagnosis, treatment planning and follow-up of KC.

Line-field optical coherence tomography: in vivo diagnosis of basal cell carcinoma subtypes compared with histopathology.

BACKGROUND: Basal cell carcinoma (BCC) is the most common skin cancer in the general population. Treatments vary from Mohs surgery to topical therapy, depending on the subtype. Dermoscopy, reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) have gained a foothold in daily clinical practice to optimize diagnosis and subtype-oriented treatment. The new technique of line-field confocal OCT (LC-OCT) allows imaging at high resolution and depth, but its use has not yet been investigated in larger studies. AIM: To evaluate the main LC-OCT criteria for the diagnosis and subtyping of BCC compared with histopathology, OCT and RCM. METHODS: In total, 52 histopathologically confirmed BCCs were evaluated for imaging criteria. Their frequency, predictive values and ROC curves were calculated. A multinominal regression with stepwise variables selection to distinguish BCC subtypes was performed. RESULTS: Nodular BCCs were mainly characterized by atypical keratinocytes, altered dermoepidermal junction (DEJ), tumour nests in the dermis, dark clefting, prominent vascularization and white hyper-reflective stroma. Superficial BCCs showed a thickening of the epidermis due to a series of tumour lobules with clear connection to the DEJ (string of pearls pattern). Infiltrative BCCs were characterized by elongated hyporeflective tumour strands, surrounded by bright collagen (shoal of fish pattern). The overall BCC subtype agreement between LC-OCT and conventional histology was 90.4% (95% CI 79.0-96.8). CONCLUSION: LC-OCT allows noninvasive, real-time identification of BCCs and their subtypes in vertical, horizontal and three-dimension mode compared with histology, RCM and OCT. Further larger studies are needed to better explore the clinical applications of this promising device.

[Noninvasive diagnostic imaging in pediatric skin lesions]. / Nichtinvasive bildgebende Diagnostik bei Hauterkrankungen im Kindesalter.

Optical coherence tomography (OCT) and reflectance confocal laser microscopy (RCM) allow noninvasive imaging diagnostics of the skin. Since the indication for a biopsy in children is generally made cautiously, OCT and KLM can be helpful in the clarification of pediatric skin lesions. In addition, biopsies only represent a snapshot of a small area of the skin, while noninvasive methods allow several locations to be examined over time, so that dynamic changes and the course of therapy can also be determined. In pediatric dermatology, these diagnostic methods are particularly suitable for the clarification of atypical pigment lesions, for infectious dermatoses such as scabies or tinea, and for the diagnosis of inflammatory and degenerative dermatoses.

Quantitative ion determination in eccrine sweat gland cells correlates to sweat reduction of antiperspirant actives.

OBJECTIVE: Axillary wetness represents an unwanted effect of the physiologically vital sweating mechanism, especially when it becomes excessive. Cosmetic products reducing sweat secretion rely on aluminium salts as the active ingredient acting by physically blocking the sweat gland. Driven by the interest to better understand the sweat mechanism and to develop alternative technologies against excessive sweating a search for an effective testing approach started as up to now, cost- and time-consuming in vivo studies represent the standard procedure for testing and identifying these alternatives. MATERIAL AND METHODS: The herein described in vitro test system is based on the measurement of intracellular changes of the ion equilibrium in cultured eccrine sweat gland cells. Subsequently, in vivo studies on the back of volunteers were conducted to verify the sweat-reducing effect of in vitro newly discovered substance. RESULTS: In this study, we describe an effective cell-based in vitro method as a potent tool for a more targeted screening of alternatives to aluminium salts. Testing the commonly used aluminium chlorohydrate as one example of an aluminium-based active in this screening procedure, we discovered a distinct influence on the ion equilibrium: Intracellular levels of sodium ions were decreased while those of chloride increased. Screening of various substances revealed a polyethyleneimine, adjusted to pH 3.5 with hydrochloric acid, to evoke the same alterations in the ion equilibrium as aluminium chlorohydrate. Subsequent in vivo studies showed its substantial antiperspirant action and confirmed the high efficiency of the polyethyleneimine solution in vivo. Further, specific investigations connecting the chloride content of the tested substances with the resulting sweat reduction pointed towards a substantial impact of the chloride ions on sweating. CONCLUSION: The newly described in vitro cell-based screening method represents an effective means for identifying new antiperspirant actives and suggests an additional biological mechanism of action of sweat-reducing ingredients which is directed towards unbalancing of the ion equilibrium inside eccrine sweat gland cells.

OBJECTIF: l'humidité axillaire représente un effet indésirable du mécanisme physiologiquement vital de la sudation, en particulier lorsqu'elle devient excessive. Les produits cosmétiques réduisant la sécrétion de sueur reposent sur les sels d'aluminium comme principe actif agissant en bloquant physiquement la glande sudoripare. Motivée par l'intérêt de mieux comprendre le mécanisme de la sudation et de développer des technologies alternatives contre l'hypersudation, une recherche pour une approche de test efficace a commencé car, jusqu'à présent, les études in vivo coûteuses et chronophages représentent la procédure standard pour tester et identifier ces alternatives. MATÉRIELS ET MÉTHODES: le système de test in vitro décrit ici est basé sur la mesure des changements intracellulaires de l'équilibre ionique dans les cellules des glandes sudoripares exocrines cultivées. Par la suite, des études in vivo sur le dos de volontaires ont été menées pour vérifier l'effet réducteur de la sudation d'une substance nouvellement découverte in vitro. RÉSULTATS: dans cette étude, nous décrivons une méthode cellulaire efficace in vitro en tant qu'outil puissant pour un dépistage plus ciblé des alternatives aux sels d'aluminium. En testant le chlorohydrate d'aluminium couramment utilisé comme exemple d'un principe actif à base d'aluminium dans cette procédure de dépistage, nous avons découvert une influence distincte sur l'équilibre ionique : les taux intracellulaires d'ions sodium ont diminué tandis que ceux du chlorure ont augmenté. La recherche de diverses substances a révélé une polyéthylèneimine, ajustée au pH 3,5 avec de l'acide chlorhydrique, pour évoquer les mêmes altérations de l'équilibre ionique que le chlorohydrate d'aluminium. Des études in vivo ultérieures ont montré son action anti-transpirante substantielle et ont confirmé la haute efficacité de la solution de polyéthylèneimine in vivo. De plus, des études spécifiques établissant un lien entre la teneur en chlorure des substances testées et la réduction de la sudation qui en résulte ont indiqué que les ions chlorure ont un impact substantiel sur l'hypersudation. CONCLUSION: la nouvelle méthode de dépistage cellulaire in vitro décrite représente un moyen efficace d'identifier de nouveaux agents anti-transpirants actifs et suggère un mécanisme d'action biologique supplémentaire des ingrédients réducteurs de la sudation, dirigé vers le déséquilibre de l'équilibre ionique à l'intérieur des cellules des glandes sudoripares exocrines.

Dynamic optical coherence tomography shows characteristic alterations of blood vessels in malignant melanoma.

BACKGROUND: Dynamic optical coherence tomography (D-OCT) allows in vivo visualization of blood vessels in the skin and in malignant tumours. Vessel patterns in malignant melanoma may be associated with tumour stage. OBJECTIVE: The aim of this study was to describe blood vessel patterns in melanomas and to correlate them with stage. METHODS: One hundred fifty-nine malignant melanomas were assessed in a multicentre study. Every tumour was imaged using D-OCT prior to surgery and histologic evaluation. The tumour data such as thickness and ulceration as well as the staging at primary diagnosis and a follow-up of at least 40 months resulted in a stage classification. The vessel patterns were assessed according to predefined categories, compared with healthy adjacent skin, and correlated to stage. RESULTS: Melanomas contained more blood vessels in different patterns compared with healthy adjacent skin. In particular, irregular vascular shapes such as blobs, coils, curves and serpiginous vessels were more common in melanomas. In addition, these patterns were significantly more often found in high-risk and metastatic melanomas than in low-risk lesions. CONCLUSION: In melanomas, the density of the blood vessels is increased, and irregular vascular patterns are more frequent. At higher stages, especially in metastatic melanomas, these atypical vessels are significantly more common.

Adapting epicutaneous patch testing protocols to assess immediate-type skin reactions.

OBJECTIVE: During the development of cosmetic formulations, in vitro and in vivo methods are essential tools used to reliably assess the skin irritation potential of a product or ingredient. Epicutaneous patch testing (single and/or multiple application protocols) has long been used as an initial in vivo method to screen for possible skin irritation properties of a substance or formulation. To confirm the mildness and dermatological and/or consumer acceptance of a product, use tests are often subsequently conducted. A study was therefore initiated to see how well patch test results correlate with use tests with respect to irritation elicited by skincare (leave-on) products. METHODS/RESULTS: A number of different cosmetic formulations were assessed in both tests. Although the patch test results did not indicate substantial irritation potentials, immediate-type reactions (stinging and redness) were observed in some volunteers which disappeared within approx. 1 h. Although transient, these reactions suggested that consumer acceptance would probably be low and the studies were discontinued. Immediate-type reactions are rare but have been described for some substances used in cosmetics. These unexpected results were nevertheless intriguing and prompted the start of a journey to see if patch test protocols could be modified to assess these reactions. An occlusive short-term patch test protocol with an application period of 20 min was developed. Successful identification of the spontaneous reactions became possible. Furthermore, there was a correlation between the intensity of reactions observed in the short-term patch test and those observed in the controlled in-use studies. Short-term patch testing using the developed protocol can therefore reliably be used as a screening method, for example in the development and optimization of cosmetic formulations containing ingredients that could cause spontaneous reactions, for instance of non-immunological contact urticaria type. CONCLUSION: The lessons learned from this studies indicate that simple modifications of existing test protocols can lead to important insights into skin reactions. These modifications can then be used to create further building blocks in the development and optimization of test strategies for cosmetic formulations which offer reliable study designs for possible reactions product developers may encounter.

OBJECTIF: Lors du développement de formulations cosmétiques, les méthodes in vitro et in vivo sont des outils essentiels utilisés pour évaluer de manière fiable le potentiel d'irritation cutanée d'un produit ou d'un ingrédient. Le test épicutané (protocoles d'application uniques et / ou multiples) est utilisé depuis longtemps comme méthode initiale in vivo pour dépister les éventuelles propriétés d'irritation cutanée d'une substance ou d'une formulation. Afin de confirmer la douceur et l'acceptation dermatologique et / ou consommateur d'un produit, des tests d'usage sont souvent effectués ultérieurement. Une étude a donc été initiée pour voir dans quelle mesure les résultats des tests épicutanés correspondent aux tests d'usage en ce qui concerne l'irritation provoquée par les produits de soin (sans rinçage). MÉTHODES/RÉSULTATS: Un certain nombre de formulations cosmétiques différentes ont été évaluées dans les deux tests. Bien que les résultats du test épicutané n'indiquent pas de potentiels d'irritation substantiels, des réactions de type immédiat (picotements et rougeurs) ont été observées chez certains volontaires. Celles-ci ont disparu en à peu près 1 heure. Bien que transitoires, ces réactions de type 5 suggéraient que l'acceptation du consommateur serait probablement faible et les études ont été interrompues. Les réactions de type immédiat 6 sont rares mais ont été évoquées en relation avec certaines substances utilisées en cosmétique. Ces résultats inattendus étaient néanmoins intrigants et ont incité le lancement d'un processus pour voir si les protocoles de test épicutané pouvaient être modifiés pour évaluer ces réactions. Un protocole de test épicutané à court terme occlusif avec une période d'application de 20 min a été développé, permettant l'identification réussie des réactions spontanées. Il a été de plus constate une corrélation entre l'intensité des réactions observées dans le test épicutané à court terme et celles observées dans les test d'usage contrôlés. Le test épicutané à court terme utilisant le protocole développé peut donc être utilisé de manière fiable comme méthode de dépistage, par exemple dans le développement et l'optimisation de formulations cosmétiques contenant des ingrédients qui pourraient provoquer des réactions spontanées, par exemple de type urticaire de contact non immunologique. CONCLUSION: Les leçons tirées de ces études indiquent que de simples modifications des protocoles de test existants peuvent révéler des informations importantes sur les réactions cutanées. Ces modifications peuvent ensuite être utilisées pour créer d'autres blocs de construction dans le développement et l'optimisation de stratégies de test pour des formulations cosmétiques qui offrent des conceptions d'études fiables pour les réactions possibles que les développeurs de produits peuvent rencontrer.

Evaluation of two histological classifications for actinic keratoses - PRO classification scored highest inter-rater reliability.

BACKGROUND: Actinic keratoses (AKs) can histologically be classified by the extent of atypical keratinocytes throughout the epidermis or their pattern of basal proliferation. Currently, no data on the inter-rater reliability of both scores is available. OBJECTIVE: To evaluate the inter-rater reliability of the two classification schemes; histological grade (AK I-III) and basal proliferation (PRO I-III). METHODS: Histological images of 54 AKs were classified by 21 independent dermatopathologists with regard to basal proliferation (PRO I-III), histological grade (AK I-III) and assumed risk of progression into invasive carcinoma. RESULTS: Overall, of the 54 AKs 16.7% (9/54) were classified as AK I, 66.7% (36/54) as AK II, and 16.7% (9/54) as AK III. With regards to basal growth pattern, 25.9% (14/54) were classified as PRO I, 42.6% (23/54) as PRO II, and 31.5% (17/54) as PRO III. We observed a highly significant inter-rater reliability for PRO-grading (P < 0.001) which was higher than for AK-grading (Kendall's W coefficient: AK = 0.488 vs. PRO = 0.793). We found substantial agreement for assumed progression risk for AKs with worsening basal proliferation (k = 0.759) compared to moderate agreement (k = 0.563) for different AK-gradings. CONCLUSIONS: Histological classification of basal growth pattern (PRO) showed higher inter-rater reliability compared to the established classification of atypical keratinocytes throughout epidermal layers. Moreover, experienced dermatopathologists considered basal proliferation to be more important in terms of progression risk than upwards directed growth patterns. It should be considered to classify AKs according to their basal proliferation pattern (PRO I-III).

[Optical coherence tomography for skin pathologies]. / Optische Kohärenztomographie bei Pathologien der Haut.

Optical coherence tomography (OCT) has become established in routine diagnosis in dermatology only in the last few years. The reason is that the skin is a challenge for OCT as a strong scattering medium, because only a very small proportion of photons is reflected and can be used for imaging. In addition, in most cases a visual assessment or a biopsy is sufficient. Nevertheless, the main field of application in dermatology is the diagnostics of epithelial skin tumors. The OCT is suitable for the early recognition of small, clinically and light microscopically unspecific basal cell carcinomas as well as for the differential diagnosis of other tumors and precancerous lesions. Using OCT, the preoperative measurement of tumor spread, observation of the course and treatment control of non-surgical procedures are possible; therefore, in many cases a biopsy or treatment control can be avoided. Dynamic OCT is a newly developed add on technique to visualize and quantify the superficial blood vessels of the skin. First studies are focused on the evaluation of tumor vessels, wound healing and monitoring of laser therapy. In ophthalmology, OCT diagnostics of basal cell carcinomas on the eyelids as well as for planning and control of eyelid interventions can be of interest.

Dynamic optical coherence tomography of skin blood vessels - proposed terminology and practical guidelines.

BACKGROUND: Dynamic optical coherence tomography (D-OCT) has recently been introduced in dermatology. In contrast to 'Standard' OCT imaging, which exclusively relies on the morphological analysis of the tissue, D-OCT allows the in vivo visualization of blood flow. Preliminary D-OCT data showed differences in the vascularization of nevus to melanoma transition, suggesting that this technology may help to differentiate between benign and malignant lesions. OBJECTIVE: Several factors may influence the quality of D-OCT imaging. Therefore, standard operating procedures as well as a common terminology are required for better validation and comparison of the images. METHODS: Here, we present practical guidelines for optimal image acquisition and a proposed terminology on vascular patterns observed by D-OCT. RESULTS: Dynamic OCT allows the morphologic distinction of different vascular shapes (e.g. dots, blobs, curves, lines), their distribution and organization within skin lesions. CONCLUSION: D-OCT adds functional information on skin microvasculature and the vascular networks within lesions.

Optical coherence tomography of basal cell carcinoma: influence of location, subtype, observer variability and image quality on diagnostic performance.

BACKGROUND: We previously described the principal results from an observational, prospective, multicentre, clinical trial of the diagnostic value of optical coherence tomography (OCT) for basal cell carcinoma (BCC) in a clinical setting. In this trial, much additional useful information was gathered that warranted further analysis, presented here. OBJECTIVES: To investigate the influence of candidate diagnostic criteria, OCT image quality, lesion location, and observer confidence and interobserver variability on the diagnostic performance of OCT, and to assess its potential use for diagnosis of BCC subtypes. METHODS: A total of 234 clinically unclear 'pink lesions' were evaluated in three steps: after clinical examination, after adding dermoscopy and after adding OCT. In addition to the diagnoses (including lesion subtype), observers recorded which of 15 diagnostic criteria the OCT image contained, their confidence in the diagnoses, the OCT image quality and the anatomical location of the lesion. RESULTS: Diagnostic performance of OCT did not depend on the lesion's anatomical location. Good OCT image quality was correlated with improved diagnostic performance, but diagnostic performance for lesions with mediocre image quality was still better than by clinical and dermoscopic examination. The main reason for reduced image quality was superficial scales and crusting. Observer confidence in diagnosis was correlated with diagnostic performance. Interobserver diagnostic performance was consistently higher than clinical examination and dermoscopy across all sites. BCC subtype could be determined with moderate accuracy, but further independent image markers are required. CONCLUSION: OCT is useful in the diagnosis of BCC.

Optical coherence tomography for margin definition of basal cell carcinoma before micrographic surgery-recommendations regarding the marking and scanning technique.

BACKGROUND/PURPOSE: Mohs Micrographic Surgery (MMS) is the preferred therapeutic treatment for high-risk basal cell carcinoma (BCC). Optical Coherence Tomography (OCT) is a non-invasive imaging technique that enables the diagnosis of BCC. We thought to determine the margins of BCCs with OCT, prior to MMS, to reduce the number of surgical steps. METHODS: Different permanent markers were tested on the skin regarding line width, resistance against disinfection and brightness in the OCT image. The visible tumor margins of BCCs were defined by dermoscopy, adding a safety margin of 2 mm and labeled using the selected pen, causing a signal shadow in OCT. Scans of the center and of entire margin were performed. If parts of the BCC were visible outside the margin, another 2 mm were added and the scan was repeated until the tissue outside the labeling looked tumor free. RESULTS: Eight out of ten BCCs were totally excised in a single stage when margin delineation was done by OCT. Macroscopic margins were enlarged after OCT scanning in four patients, saving further stages of MMS. CONCLUSION: OCT may help to better define the microscopic dimensions of BCCs and therefore reduce the number of stages of MMS.

In vivo microvascular imaging of cutaneous actinic keratosis, Bowen's disease and squamous cell carcinoma using dynamic optical coherence tomography.

BACKGROUND: A clear distinction between actinic keratosis (AK), Bowen's disease (BD) and squamous cell carcinoma (SCC) cannot reliably be made by clinical and dermoscopic evaluation alone. Dynamic optical coherence tomography (D-OCT) is a novel angiographic variant of OCT that allows for non-invasive, in vivo evaluation of the cutaneous microvascular morphology. OBJECTIVE: To investigate the microvascular structures of AK, BD and invasive SCC using D-OCT in order to gain insights into the microvascular morphology of lesions in the spectrum of keratinocyte skin cancers. METHODS: Forty-seven patients with a total of 54 lesions (18 AK, 12 BD and 24 SCC) were included in the study. D-OCT still images of AK, BD and SCC at three predefined skin depths were prepared and randomized, creating a study set of 162 D-OCT images. Three observers performed blinded evaluations of the randomized study set assessing multiple parameters including the different types of vascular morphology. Non-blinded quantitative measurements of vascular diameter were also performed. RESULTS: The blinded observer analysis suggests that D-OCT evaluation of the vascular morphology may aid in distinguishing AK, BD and SCC lesions. We identified two vascular shapes that presented significantly differently across the lesion types, namely 'blobs' and 'curves'. A strong presence of blobs at 300 µm skin depth was characteristically seen in a third of BD cases, while not or only slightly present in AK and SCC lesions. Vascular curves were predominantly present in AK lesions. CONCLUSION: We identified various vascular D-OCT features that may aid in non-invasively differentiating subtypes within the keratinocyte skin cancer spectrum.

Shining into the White: The Spectrum of Epithelial Tumors from Actinic Keratosis to Squamous Cell Carcinoma.

Actinic keratosis, Bowen disease, and invasive squamous cell carcinoma represent different steps within the disease continuum of squamous neoplasia. Although these stages of squamous neoplasia share common findings, reflectance confocal microscopy may be applied for their differentiation and distinction from other benign or malignant lesions. Hyperkeratosis represents the most important limitation in the evaluation of squamous neoplasia as it may impair the analysis of deeper epidermal and dermal structures significantly.