Actinic keratoses show variable histological basal growth patterns - a proposed classification adjustment

High efficacy of red light photodynamic therapy with 10 % aminolevulinic acid gel irrespective of the extent of keratinocyte atypia in actinic keratosis - exploratory post-hoc analysis of three pivotal phase III trials

BACKGROUND

Primary endpoints of clinical studies investigating treatments for actinic keratosis (AK) are mainly based on clinical evaluation, but a recent study showed that in AK, clinical classification according to Olsen and the extent of keratinocyte atypia do not necessarily correlate. The influence of the epidermal extent of atypia on treatment efficacy is usually not investigated and therefore remains largely unknown.

OBJECTIVE

To evaluate whether the extent of keratinocyte atypia influences efficacy of photodynamic therapy (PDT) when treating AK.

METHODS

We performed a post-hoc analysis of histological (keratinocyte intraepithelial neoplasia (KIN)), and clinical (Olsen) data of biopsied lesions of three pivotal studies evaluating PDT using 10 % aminolevulinic acid (ALA) gel or vehicle and narrow- or broad-spectrum red light lamps.

RESULTS

Overall, 514 biopsied lesions were considered. Clearance rates after red light PDT with 10 % ALA gel were comparable for KIN I-III (88.2 %, 92.0 % and 87.9 %) and Olsen I-II lesions for any given lamp type. Generally, clearance rates were higher using narrow- compared to broad-spectrum lamps. For both lamp types, the variation in clearance rates from KIN I-III was low. Clearance was lower with vehicle.

LIMITATIONS

Varying lesion numbers in the subgroups and a remaining risk of bias due to the biopsies are potential limitations.

CONCLUSION

Our results suggest that red light PDT with 10 % ALA gel is an effective treatment option for AK regardless of the extent of keratinocyte atypia.

[Update in the diagnosis and treatment of actinic keratosis]

Actinic keratosis (AK) is among the most common conditions in dermatology in an increasingly aging population. However, the presence of severe field cancerization with large treatment fields showing multiple lesions with distinct features often poses a therapeutic challenge. The most accurate possible characterization of the treatment field, risk assessment concerning the occurrence of cutaneous squamous cell carcinoma, and knowledge of the efficacy and local side effects of the available interventions are of paramount importance for effective management and preventive efforts. This article summarizes current developments in the diagnosis and treatment of AK and discusses their application in everyday clinical practice. In particular, the focus is on the increasing value of non-invasive diagnostic techniques like "line-field" confocal optical coherence tomography, and the recently approved topical agents tirbanibulin 1% ointment and 5‑fluorouracil 4% cream, as well as current developments of photodynamic therapy and prevention.

Diagnosis and therapy of actinic keratosis

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO score) seem to drive malignant transformation, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease, and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimens, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Diagnose und Therapie aktinischer Keratosen

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO Score) seem to drive malignant turnover, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO Score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimes, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Line-field confocal optical coherence tomography in dermato-oncology: A literature review towards harmonized histopathology-integrated terminology

Non-invasive diagnostics like line-field confocal optical coherence tomography (LC-OCT) are being implemented in dermato-oncology. However, unification of terminology in LC-OCT is lacking. By reviewing the LC-OCT literature in the field of dermato-oncology, this study aimed to develop a unified terminological glossary integrated with traditional histopathology. A PRISMA-guided literature-search was conducted for English-language publications on LC-OCT of actinic keratosis (AK), keratinocyte carcinoma (KC), and malignant melanoma (MM). Study characteristics and terminology were compiled. To harmonize LC-OCT terminology and integrate with histopathology, synonymous terms for image features of AK, KC, and MM were merged by two authors, organized by skin layer and lesion-type. A subset of key LC-OCT image-markers with histopathological correlates that in combination were typical of AK, squamous cell carcinoma in situ (SCCis), invasive squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and MM in traditional histopathology, were selected from the glossary by an experienced dermatopathologist. Seventeen observational studies of AK (7 studies), KC (13 studies), MM (7 studies) utilizing LC-OCT were included, with 117 terms describing either AK, KC, or MM. These were merged to produce 45 merged-terms (61.5% reduction); 5 assigned to the stratum corneum (SC), 23 to the viable epidermis, 2 to dermo-epidermal junction (DEJ) and 15 to the dermis. For each lesion, mandatory key image-markers were a well-defined DEJ and presence of mild/moderate but not severe epidermal dysplasia for AK, severe epidermal dysplasia and well-defined DEJ for SCCis, interrupted DEJ and/or dermal broad infiltrative strands for invasive SCC, dermal lobules connected and/or unconnected to the epidermis for BCC, as well as single atypical melanocytes and/or nest of atypical melanocytes in the epidermis or dermis for MM. This review compiles evidence on LC-OCT in dermato-oncology, providing a harmonized histopathology-integrated terminology and key image-markers for each lesion. Further evaluation is required to determine the clinical value of these findings.

Demystifying oral epithelial dysplasia: a histological guide

Oral epithelial dysplasia is a histologically diagnosed potentially premalignant disorder of the oral mucosa, which carries a risk of malignant transformation to squamous cell carcinoma. The diagnosis and grading of oral epithelial dysplasia is challenging, with cases often referred to specialist oral and maxillofacial pathology centres for second opinion. Even still there is poor inter-examiner and intra-examiner agreement in a diagnosis. There are a total of 28 features of oral epithelial dysplasia listed in the 5th edition of World Health Organization classification of tumours of the head and neck. Each of these features is poorly defined and subjective in its interpretation. Moreover, how these features contribute to dysplasia grading and risk stratification is even less well defined. This article discusses each of the features of oral epithelial dysplasia with examples and provides an overview of the common mimics, including the normal histological features of the oral mucosa which may mimic atypia. This article also highlights the paucity of evidence defining these features while offering suggested definitions. Ideally, these definitions will be refined, and the most important features identified to simplify the diagnosis of oral epithelial dysplasia. Digital whole slide images of the figures in this paper can be found at: https://www.pathogenesis.co.uk/r/demystifying-dysplasia-histology-dataset.

Line-Field Confocal Optical Coherence Tomography (LC-OCT) for Skin Imaging in Dermatology

Line-field confocal optical coherence tomography (LC-OCT) is a non-invasive optical imaging technique based on a combination of the principles of optical coherence tomography and reflectance confocal microscopy with line-field illumination, which can generate cell-resolved images of the skin in vivo. This article reports on the LC-OCT technique and its application in dermatology. The principle of the technique is described, and the latest technological innovations are presented. The technology has been miniaturized to fit within an ergonomic handheld probe, allowing for the easy access of any skin area on the body. The performance of the LC-OCT device in terms of resolution, field of view, and acquisition speed is reported. The use of LC-OCT in dermatology for the non-invasive detection, characterization, and therapeutic follow-up of various skin pathologies is discussed. Benign and malignant melanocytic lesions, non-melanocytic skin tumors, such as basal cell carcinoma, squamous cell carcinoma and actinic keratosis, and inflammatory and infectious skin conditions are considered. Dedicated deep learning algorithms have been developed for assisting in the analysis of LC-OCT images of skin lesions.

Where Artificial Intelligence Can Take Us in the Management and Understanding of Cancerization Fields

Squamous cell carcinoma and its precursor lesion actinic keratosis are often found together in areas of skin chronically exposed to sun, otherwise called cancerisation fields. The clinical assessment of cancerisation fields and the correct diagnosis of lesions within these fields is usually challenging for dermatologists. The recent adoption of skin cancer diagnostic imaging techniques, particularly LC-OCT, helps clinicians in guiding treatment decisions of cancerization fields in a non-invasive way. The combination of artificial intelligence and non-invasive skin imaging opens up many possibilities as AI can perform tasks impossible for humans in a reasonable amount of time. In this text we review past examples of the application of AI to dermatological images for actinic keratosis/squamous cell carcinoma diagnosis, and we discuss about the prospects of the application of AI for the characterization and management of cancerization fields.

KI-basierte Bestimmung des PRO-Scores in aktinischen Keratosen anhand von LC-OCT-Bilddatensätzen: Artificial intelligence-based PRO score assessment in actinic keratoses from LC-OCT imaging using Convolutional Neural Networks

Hintergrund

Mit Hilfe des histologischen PRO‐Scores (I–III) kann das Risiko einer malignen Transformation aktinischer Keratosen (AK) abgeschätzt werden, indem er das Ausmaß der Undulation und basalen Proliferation der dermoepidermalen Junktionszone (DEJ) bewertet. Die konfokale Line‐Field optische Kohärenztomographie (LC‐OCT) ermöglicht eine nichtinvasive Bestimmung des PRO‐Scores in Echtzeit. Anhand von LC‐OCT‐Bilddatensätzen kann eine künstliche Intelligenz (KI) mit Hilfe von Convolutional Neural Networks (CNN) zur automatischen Quantifizierung des PRO‐Scores von AK in vivo trainiert werden.

Patienten und Methodik

Convolutional Neural Networks wurden trainiert, um LC‐OCT‐Bilder von gesunder Haut und von AK zu segmentieren. PRO‐Score‐Modelle wurden in Übereinstimmung mit dem histopathologischen Goldstandard entwickelt und an einer Teilmenge von 237 LC‐OCT‐AK‐Bildern trainiert und an 76 Bildern getestet, wobei der von der KI‐berechnete PRO‐Score mit dem visuellen Konsens der Bildgebungsexperten verglichen wurde.

Ergebnisse

Eine signifikante Übereinstimmung wurde in 57/76 (75%) Fällen festgestellt. Die KI‐basierte Bewertung des PRO‐Scores korrelierte am besten mit dem visuellen Score für PRO II (84,8%) vs. PRO III (69,2%) vs. PRO I (66,6%). In 25% der Fälle kam es zu Fehlinterpretationen, die meist auf eine Verschattung der DEJ sowie störende Merkmale wie Haarfollikel zurückzuführen waren.

Schlussfolgerungen

Die Ergebnisse deuten darauf hin, dass CNN für die automatische Quantifizierung des PRO‐Scores in LC‐OCT‐Bilddatensätzen hilfreich sind. Dies könnte zur nichtinvasiven Bewertung des Proliferationsrisikos in der Diagnostik und Nachsorge von AK herangezogen werden.

Artificial intelligence-based PRO score assessment in actinic keratoses from LC-OCT imaging using Convolutional Neural Networks

BACKGROUND AND OBJECTIVES

The histological PRO score (I-III) helps to assess the malignant potential of actinic keratoses (AK) by grading the dermal-epidermal junction (DEJ) undulation. Line-field confocal optical coherence tomography (LC-OCT) provides non-invasive real-time PRO score quantification. From LC-OCT imaging data, training of an artificial intelligence (AI), using Convolutional Neural Networks (CNNs) for automated PRO score quantification of AK in vivo may be achieved.

PATIENTS AND METHODS

CNNs were trained to segment LC-OCT images of healthy skin and AK. PRO score models were developed in accordance with the histopathological gold standard and trained on a subset of 237 LC-OCT AK images and tested on 76 images, comparing AI-computed PRO score to the imaging experts' visual consensus.

RESULTS

Significant agreement was found in 57/76 (75%) cases. AI-automated grading correlated best with the visual score for PRO II (84.8%) vs. PRO III (69.2%) vs. PRO I (66.6%). Misinterpretation occurred in 25% of the cases mostly due to shadowing of the DEJ and disruptive features such as hair follicles.

CONCLUSIONS

The findings suggest that CNNs are helpful for automated PRO score quantification in LC-OCT images. This may provide the clinician with a feasible tool for PRO score assessment in the follow-up of AK.

Innovation in Actinic Keratosis Assessment: Artificial Intelligence-Based Approach to LC-OCT PRO Score Evaluation

Actinic keratosis (AK) is a common skin cancer in situ that can progress to invasive SCC. Line-field confocal optical coherence tomography (LC-OCT) has emerged as a non-invasive imaging technique that can aid in diagnosis. Recently, machine-learning algorithms have been developed that can automatically assess the PRO score of AKs based on the dermo-epidermal junction's (DEJ's) protrusion on LC-OCT images. A dataset of 19.898 LC-OCT images from 80 histologically confirmed AK lesions was used to test the performance of a previous validated artificial intelligence (AI)-based LC-OCT assessment algorithm. AI-based PRO score assessment was compared to the imaging experts' visual score. Additionally, undulation of the DEJ, the number of protrusions detected within the image, and the maximum depth of the protrusions were computed. Our results show that AI-automated PRO grading is highly comparable to the visual score, with an agreement of 71.3% for the lesions evaluated. Furthermore, this AI-based assessment was significantly faster than the regular visual PRO score assessment. The results confirm our previous findings of the pilot study in a larger cohort that the AI-based grading of LC-OCT images is a reliable and fast tool to optimize the efficiency of visual PRO score grading. This technology has the potential to improve the accuracy and speed of AK diagnosis and may lead to better clinical outcomes for patients.

Basal Proliferation and Acantholysis May Represent Histological High-Risk Factors for Progression into Invasive Squamous Cell Carcinoma: A Comparison Study in Solid Organ Transplant Recipients and Matched Immunocompetent Patients

Histological risk factors of AKs cannot be directly determined. Recent studies indicate that AKs restricted to the lower third of the epidermis (AK I), with marked basal proliferation (PRO III) and acantholysis, are associated with an increased risk of progression to invasive squamous cell carcinoma (iSCC). To confirm the aforementioned histological risk factors, this study compared AKs from solid organ transplant recipients (sOTRs), known to carry an up to 250-fold higher risk for progression into iSCC, to a matched immunocompetent control group (ICG). In total, 111 AKs from 43 sOTRs showed more AKs (n = 54, 48.7%) graded as AK I compared to 35 AKs (31.5%) in the ICG (p = 0.009). In line with these findings, 89 AKs (80.2%) from sOTRs showed pronounced basal proliferation (PRO III) compared to 37 AKs (33.3%) in the ICG (p < 0.0001). Acantholysis was more frequent in sOTRs than the ICG (59.5% vs. 32.4%, p < 0.0001) and more frequently associated with advanced basal proliferation (p < 0.0001). In conclusion, this study showed that acantholytic AKs graded as AK I and PRO III are predominantly found in a population at high risk of iSCC. Thus, AKs with marked basal proliferation and acantholysis should be assumed to be histological high-risk factors for the progression into iSCC.

Factors for risk stratification of patients with actinic keratosis using integrated analysis of clinicopathological features and gene expression patterns

BACKGROUND

Actinic keratosis (AK) is considered as precursor lesion of invasive squamous cell carcinoma. Molecular studies on AK are limited because of too small size of the biopsy specimen to obtain enough DNA or RNA.

METHODS

Twenty biopsy cases of AK, followed by second same-sited biopsies, were included. Ten cases were diagnosed with total regression (regression group), while the other 10 were diagnosed with invasive carcinoma (progression group) in the follow-up biopsies. Using digital spatial profiling (DSP) technology, whole-gene expression analysis defined by specific regions of interest was performed for all 20 cases. After the clinicopathological features were assessed, separate and integrated analyses of these features and gene expression patterns were performed using machine-learning technology. All analyses were performed on both lesion keratinocytes (KT) and infiltrated stromal lymphocytes (LC).

RESULTS

Among the 18,667 genes assessed, 33 and 72 differentially expressed genes (DEGs) between the regression and progression groups were found in KT and LC respectively. The primary genes distinguishing the two groups were KRT10 for KT and CARD18 for LC. Clinicopathological features were weaker in risk stratification of AK progression than the gene expression patterns. Pathways associated with various cancers were upregulated in the progression group of KT, whereas the nucleotide-binding oligomerization domain (NOD)-like receptor signalling pathway was upregulated in the progression of LC.

CONCLUSION

Gene expression patterns were effective for risk stratification of AK progression, and their distinguishing power was higher than that of clinicopathological features.

Early clinical response to 5-fluorouracil 0.5% and salicylic acid 10% topical solution in the treatment of actinic keratoses of the head: an observational study

BACKGROUND

Actinic keratosis is one of the most common dermatological disorders. A new topical solution, constituted by 0.5% 5-fluorouracil and 10% salicylic acid (Actikerall, Almirall) has been introduced in the treatment pipeline of non-hyperkeratotic actinic keratoses of the head and neck.

PATIENTS AND METHODS

We analyzed in an observational prospective clinical study the short-term treatment effectiveness of 5-fluorouracil and salicylic acid on face and scalp actinic keratoses of grade 1 and 2 of forty patients. Efficacy assessment was performed by clinical dermatological examination, collecting color photographs, calculating AKASI score, and by means of dermoscopy for each target lesion at every visit.

RESULTS

AKASI score decreased from an initial score of 3.3 to a final score of 0.9. At week 4, we were able to record a complete clearance of 50% of the treated lesions and a partial clearance of 28%. At the end of 12 weeks, 84% of the total lesions showed complete clearance, while 8% had partial clearance.

CONCLUSIONS

5-fluorouracil and salicylic acid topical solution is effective in the treatment of mild to moderate actinic keratoses. In the future, further studies are needed to evaluate the chance of adjusting drug dosage according to patients' and actinic keratoses features.

Topical Pharmacotherapy for Actinic Keratoses in Older Adults

Actinic keratosis is caused by excessive lifetime sun exposure. It must be treated, regardless of thickness, because it is the biologic precursor of invasive squamous cell carcinoma, a potentially deadly malignancy. Physical ablative techniques such as cryotherapy, lasers, and curettage are the most used treatments for isolated lesions. Multiple lesions are treated with topical drugs, chemical peelings, and physical techniques. Drug preparations containing diclofenac plus hyaluronate, aminolevulinic acid, and methyl aminolevulinate and different concentrations of imiquimod and 5-fluorouracil are approved for this clinical indication. All treatments have a good profile of efficacy and tolerability although there are relevant differences in the clearance rate, tolerability, and type and frequency of adverse effects. In addition, they have very different mechanisms of action and treatment protocols. No differences in the efficacy and tolerability were found in older patients compared with younger patients, therefore no dose adjustments are needed. That said, older patients often need to be motivated to treat actinic keratoses and a careful attention to expectations, needs, and preferences should be used to obtain the maximal adherence and prevent treatment failure. This goal can be achieved with a careful evaluation not only of published efficacy, toxicity, and tolerability data but also of practical topics such as the frequency of daily applications, the overall duration of therapy, and the need for a caregiver. Finally, particular attention must be paid in the case of frail patients and immunosuppressed patients.

Line-field confocal optical coherence tomography for actinic keratosis and squamous cell carcinoma: a descriptive study

BACKGROUND

Early and accurate diagnosis of cutaneous squamous cell carcinomas (SCCs) and actinic keratoses (AK) is fundamental to reduce their associated morbidity and to select the correct treatment. Line-field confocal optical coherence tomography (LC-OCT) is a new imaging device that can characterize healthy skin and basal cell carcinoma, but no large studies on keratinocyte cell tumours have yet been published.

AIM

To identify and describe LC-OCT criteria associated with SCC and AK, and to compare LC-OCT findings in these tumours.

METHODS

A retrospective observational multicentre study was conducted. Lesions were imaged with the LC-OCT device before surgery and examined histologically. LC-OCT criteria for AK/SCC were identified and their presence was evaluated in all study lesions. Univariate and multivariate analyses were performed to compare AK and SCCs, and to investigate differences between in situ and invasive tumours.

RESULTS

In total, 158 patients with 50 AK and 108 SCCs (62 in situ and 46 invasive) were included. Cytological and architectural alterations were found in most lesions, and differences were found between AK and SCCs. Although the visualization of the dermoepidermal junction (DEJ) was often hampered by hyperkeratosis and acanthosis, an outlined DEJ without broad strands was observed in almost all AK and almost all in situ SCCs, but in only three invasive SCCs (P < 0.001) when the DEJ was detectable.

CONCLUSION

Our results suggest that LC-OCT can help clinicians in the identification of AK and SCC and their differentiation, providing a real-time and noninvasive examination. Further studies are needed to confirm our data.

Metabolomic Analysis of Actinic Keratosis and SCC Suggests a Grade-Independent Model of Squamous Cancerization

Simple Summary

Actinic keratoses (AKs) are the most common sun-induced precancerous lesions that can progress to squamocellular carcinoma (SCC). AK I have been considered low-risk lesions, often evolving into AK II, the AK grade II and III have the potential to evolve to SCC. This research has assessed the metabolomic fingerprints of AK I, AK II, AK III and SCC by HR-MAS NMR spectroscopy, with the aim of evaluating the hypothesis of grade-association AK to SCC. The association between AKs and SCCs has also been evaluated by histopathology. Our findings support the notion that AK I are different from healthy skin and share different features with SCCs, indeed, they are metabolically active lesions with metabolic profiles similar to high-grade AKs and to SCC. The negative association of AKs with parakeratosis and the positive association with hypertrophy also suggested a similar behavior between AKs and SCCs. Therefore, all AKs should be treated independently from their clinical appearance or histological grade, since it is not possible to predict their potential evolution to SCC.

Abstract

Background—Actinic keratoses (AKs) are the most common sun-induced precancerous lesions that can progress to squamocellular carcinoma (SCC). Recently, the grade-independent association between AKs and SCC has been suggested; however, the molecular bases of this potential association have not been investigated. This study has assessed the metabolomic fingerprint of AK I, AK II, AK III and SCC using high resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) spectroscopy in order to evaluate the hypothesis of grade-independent association between AK and SCC. Association between AKs and SCCs has also been evaluated by histopathology. Methods—Metabolomic data were obtained through HR-MAS NMR spectroscopy. The whole spectral profiles were analyzed through multivariate statistical analysis using MetaboAnalyst 5.0. Histologic examination was performed on sections stained with hematoxylin and eosin; statistical analysis was performed using STATA software version 14. Results—A group of 35 patients affected by AKs and/or SCCs and 10 healthy controls were enrolled for metabolomics analysis. Histopathological analysis was conducted on 170 specimens of SCCs and AKs (including the ones that underwent metabolomic analysis). SCCs and AK I were found to be significantly associated in terms of the content of some metabolites. Moreover, in the logistic regression model, the presence of parakeratosis in AKs appeared to be less frequently associated with SCCs, while AKs with hypertrophy had a two-fold higher risk of being associated with SCC. Conclusions—Our findings, derived from metabolomics and histopathological data, support the notion that AK I are different from healthy skin and share some different features with SCCs. This may further support the expanding notion that all AKs should be treated independently from their clinical appearance or histological grade because they may be associated with SCC.

In Vivo Reflectance Confocal Microscopy as a Response Monitoring Tool for Actinic Keratoses Undergoing Cryotherapy and Photodynamic Therapy

Simple Summary

The assessment of actinic keratoses (AKs) in prevention and therapeutic trials, as well as clinical practice, could significantly benefit from the incorporation of non-invasive imaging technology. Such technology has the potential to enhance the objective evaluation of clinical and subclinical AKs with the added advantage of sequential monitoring. In vivo reflectance confocal microscopy (RCM) allows for the non-invasive imaging of AKs at a cellular level. We aimed to establish an in in vivo RCM protocol for AK response monitoring, ultimately leading to more reliable characterization of longitudinal responses and therapy optimization.

Abstract

Reflectance confocal microscopy (RCM) presents a non-invasive method to image actinic keratosis (AK) at a cellular level. However, RCM criteria for AK response monitoring vary across studies and a universal, standardized approach is lacking. We aimed to identify reliable AK response criteria and to compare the clinical and RCM evaluation of responses across AK severity grades. Twenty patients were included and randomized to receive either cryotherapy (n = 10) or PDT (n = 10). Clinical assessment and RCM evaluation of 12 criteria were performed in AK lesions and photodamaged skin at baseline, 3 and 6 months. We identified the RCM criteria that reliably characterize AK at baseline and display significant reduction following treatment. Those with the highest baseline odds ratio (OR), good interobserver agreement, and most significant change over time were atypical honeycomb pattern (OR: 12.7, CI: 5.7–28.1), hyperkeratosis (OR: 13.6, CI: 5.3–34.9), stratum corneum disruption (OR: 7.8, CI: 3.5–17.3), and disarranged epidermal pattern (OR: 6.5, CI: 2.9–14.8). Clinical evaluation demonstrated a significant treatment response without relapse. However, in grade 2 AK, 10/12 RCM parameters increased from 3 to 6 months, which suggested early subclinical recurrence detection by RCM. Incorporating standardized RCM protocols for the assessment of AK may enable a more meaningful comparison across clinical trials, while allowing for the early detection of relapses and evaluation of biological responses to therapy over time.

Guidelines of care for the management of actinic keratosis

BACKGROUND

Actinic keratoses (AK) are rough scaly patches that arise on chronically ultraviolet-exposed skin and can progress to keratinocyte carcinoma.

OBJECTIVE

This analysis examined the literature related to the management of AK to provide evidence-based recommendations for treatment. Grading, histologic classification, natural history, risk of progression, and dermatologic surveillance of AKs are also discussed.

METHODS

A multidisciplinary Work Group conducted a systematic review to address 5 clinical questions on the management of AKs and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach for assessing the certainty of the evidence and formulating and grading clinical recommendations. Graded recommendations were voted on to achieve consensus.

RESULTS

Analysis of the evidence resulted in 18 recommendations.

LIMITATIONS

This analysis is based on the best available evidence at the time it was conducted. The pragmatic decision to limit the literature review to English language randomized trials may have excluded data published in other languages or limited identification of relevant long-term follow-up data.

CONCLUSIONS

Strong recommendations are made for using ultraviolet protection, topical imiquimod, topical 5-fluorouracil, and cryosurgery. Conditional recommendations are made for the use of photodynamic therapy and diclofenac for the treatment of AK, both individually and as part of combination therapy regimens.

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.

In-Vivo LC-OCT Evaluation of the Downward Proliferation Pattern of Keratinocytes in Actinic Keratosis in Comparison with Histology: First Impressions from a Pilot Study

It is known that actinic keratoses (AKs) can progress to invasive squamous cell carcinoma (SCC). The histological PRO grading of AKs is based on the growth pattern of basal keratinocytes and relates to their progression risk. AKs can be non-invasively characterized by line-field confocal optical coherence tomography (LC-OCT). The aim of the study was to define criteria for an LC-OCT grading of AKs based on the PRO classification and to correlate it with its histological counterpart. To evaluate the interobserver agreement for the LC-OCT PRO classification, fifty AKs were imaged by LC-OCT and biopsied for histopathology. PRO histological grading was assessed by an expert consensus, while two evaluator groups separately performed LC-OCT grading on vertical sections. The agreement between LC-OCT and histological PRO grading was 75% for all lesions (weighted kappa 0.66, 95% CI 0.48-0.83, p ≤ 0.001) and 85.4% when comparing the subgroups PRO I vs. PRO II/III (weighted kappa 0.64, 95% CI 0.40-0.88, p ≤ 0.001). The interobserver agreement for LC-OCT was 90% (Cohen's kappa 0.84, 95% CI 0.71-0.91, p ≤ 0.001). In this pilot study, we demonstrated that LC-OCT is potentially able to classify AKs based on the basal growth pattern of keratinocytes, in-vivo reproducing the PRO classification, with strong interobserver agreement and a good correlation with histopathology.

Treatment-resistant actinic keratoses are characterized by distinct clinical and histological features

BACKGROUND

Actinic keratoses (AK) are generally treated to reduce the risk of progression into invasive cutaneous squamous cell carcinoma (cSCC). However, this risk of transformation is low, and rather than focusing on these lesions, current treatment studies report on complete clearance of AKs in an entire field. This study aimed to investigate treatment-resistant AKs (trAK) after field therapy compared to randomly chosen AKs prior to treatment.

METHODS

AKs were clinically assessed according to the grade of hyperkeratosis and pain on palpation, prior to treatment. TrAKs were biopsied and compared to AKs which were biopsied prior to any treatment. AKs were evaluated regarding histological severity (AKI-III), their basal growth grading (PROI-III), acantholysis, elastosis, follicular extension of atypical keratinocytes and accompanying infiltrate.

RESULTS

Two hundred eleven AKs in 171 patients were identified. TrAKs (N.=79) were significantly more painful (64.6% vs. 22.0%; P<0.0001), showing acantholysis (57.0% vs. 33.3%; P=0.0007); and with distinct basal proliferation (PROIII) (64.4% vs. 46.2%; P=0.0099) compared to the control group (N.=132). In a multivariate analysis using logistic regression, pain and PRO III graded lesions were significant independent (P<0.0001 and P=0.0179) predictors for trAKs. Focusing on individual histological features in the trAK group, AKs with grade AKIII, PROIII or follicular extension reaching the sebaceous gland were the most common findings with 51.9%, 64.6%, and 59.5% AKs demonstrating this, respectively.

CONCLUSIONS

TrAKs are often painful, showing a distinct basal proliferation (PROIII) and acantholysis. As these features are also seen in invasive cSCCs, trAKs may represent a subgroup of AKs and, for this reason, it requires further evaluations.

Developments and challenges in dermatology: an update from the Interactive Derma Academy (IDeA) 2019

The 2019 Interactive Derma Academy (IDeA) meeting was held in Lisbon, Portugal, 10-12 May, bringing together leading dermatology experts from across Europe, the Middle East and Asia. Over three days, the latest developments and challenges in relation to the pathophysiology, diagnosis, evaluation and management of dermatological conditions were presented, with a particular focus on acne, atopic dermatitis (AD) and actinic keratosis (AK). Interesting clinical case studies relating to these key topics were discussed with attendees to establish current evidence-based best practices. Presentations reviewed current treatments, potential therapeutic approaches and key considerations in the management of acne, AK and AD, and discussed the importance of the microbiome in these conditions, as well as the provision of patient education/support. It was highlighted that active treatment is not always required for AK, depending on patient preferences and clinical circumstances. In addition to presentations, two interactive workshops on the diagnosis and treatment of sexually transmitted infections/diseases (STIs/STDs) presenting to the dermatology clinic, and current and future dermocosmetics were conducted. The potential for misdiagnosis of STIs/STDs was discussed, with dermoscopy and/or reflectance confocal microscopy suggested as useful diagnostic techniques. In addition, botulinum toxin was introduced as a potential dermocosmetic, and the possibility of microbiome alteration in the treatment of dermatological conditions emphasized. Furthermore, several challenges in dermatology, including the use of lasers, the complexity of atopic dermatitis, wound care, use of biosimilars and application of non-invasive techniques in skin cancer diagnosis were reviewed. In this supplement, we provide an overview of the presentations and discussions from the fourth successful IDeA meeting, summarizing the key insights shared by dermatologists from across the globe.

Evaluation of dermatoscopic criteria for early detection of squamous cell carcinoma arising on an actinic keratosis

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.

[Actinic keratosis]

Actinic keratoses (AK) are common precancerous cutaneous lesions in fair-skinned individuals as a result of cumulative exposure to ultraviolet radiation. Due to their high prevalence, AK account for a large disease burden, in particular in older persons. As AK may potentially progress into invasive cutaneous squamous cell carcinoma, guidelines recommend early and consequent treatment. Numerous lesion- and field-directed interventions with different efficacy and safety profiles are currently licensed in Germany. The appropriate intervention should be chosen together with the patient based on his or her motivation and expectations towards the treatment.

[Actinic keratoses : Current guideline and practical recommendations]

The S3 guideline "Actinic keratosis and squamous cell carcinoma of the skin" was published on 30 June 2019. Subsequently, publications, reviews and meta-analyses appeared with new questions regarding the comparability of study data and heterogeneity of the evaluations, which are caused, among other things, by divergent measurement parameters as well as insufficient consideration of pretreatments and combined treatments. This concise overview was written in the context of criticism and in view of necessary developments and research. Topics include epidemiology, pathogenesis, prevention, clinical presentation, therapy and BK5103. Therapy is divided into local destructive procedures and topical applications. Recommendations with quotation marks are based on the actual guideline. Corresponding evidence levels are given. For the implementation in daily routine basic data, side effects and features of therapeutic options are mentioned. The current developments and questions concerning actinic keratoses become clear.

Histological classification of cutaneous squamous cell carcinomas with different severity

Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer. Histology represents the gold standard to confirm the diagnosis of cSCC and is mandatory to determine important findings for tumour grading, such as tumour thickness, depth of invasion, degree of differentiation and histological subtype, perineural and vascular invasion, and assessing tumour margins. In daily clinical practice, the combination of clinical and histological features should be considered when grading the tumours and treating the patients, accordingly. This article aims to provide a structured overview of the most common histological findings of in situ and invasive cSCCs, namely those relevant to their severity, and should facilitate the understanding and evaluation of these results.

Assessment of 5-Aminolaevulinic Acid Photodynamic Therapy (ALA-PDT) in Chinese patients with actinic keratosis: Correlation of dermoscopic features with histopathology

OBJECTIVES

The study examines the changes in dermoscopic features of actinic keratosis (AK) after photodynamic therapy, and delineates the association between AK dermoscopic and histopathological findings.

METHODS

A total of 21 patients (23 lesions) with pathologically confirmed actinic keratosis who received 5-aminolaevulinic acid (ALA) photodynamic therapy (ALA-PDT) were enrolled. The numbers of PDT treatments were: 1, n = 1; 2, n = 2; 3, n = 10; 4, n = 6; 5, n = 2; 6, n = 2). The dermoscopic features before and after the PDT were compared.

RESULTS

There were statistically significant decreases in the positive rates of dermoscopic features including scales (P < 0.001), follicular plugs with whitish halo (P = 0.013), and red pseudonetwork (P = 0.022) among patients treated with ALA-PDT. Dermoscopic feature was significantly associated with pathological grade (P < 0.001). Histopathological hyperkeratosis was significantly associated with dermoscopic red pseudonetwork (P = 0.034) and wavy vessel (P = 0.005). Parakeratosis was associated with wavy vessels (P = 0.001). For vascular hyperplasia in dermal papillae, the significant correlates included scales (P = 0.011), follicular plugs with whitish halo (P = 0.011), red pseudonetwork (P < 0.001); coiled vessels (P = 0.003) and rosette sign (P = 0.004). Wavy vessels was the only feature correlating keratosis pilaris (P = 0.003).

CONCLUSIONS

The findings of the present study support dermoscopy as having potential to be useful for diagnosing and monitoring of actinic keratosis.

Actinic keratosis: where do we stand and where is the future going to take us?

Introduction: Actinic keratosis (AK) is a chronic disease which is mainly located across areas of sun-exposed skin. Clinical and subclinical lesions coexist across a large area resulting in a field cancerization. As these lesions have the potential to transform into invasive squamous cell carcinoma (iSCC), treatment is crucial. With global prevalence increasing, AK is expected to be the most common in situ carcinoma of the skin.Areas covered: In this article, we cover the established algorithm of treating AK and give an insight into the drugs under development. There are six compounds under development covering different treatment angles, from Sinecatechin a Polyphenon E which targets the link between HPV infection and development of AK, over Tirbanibulin which targets the SRC proto-oncogene and fast proliferating cells, to Tuvatexib a small-molecule dual VDAC/HK2 modulator that has shown that it can compete with the established therapies.Expert opinion: These new treatment options are moving us further toward a more individually tailored treatment for each patient considering his abilities, the size and location of his lesions but also the genetic bases as well as individual risk of transforming into a iSCC and possibly other factors contributing to each patients individual AK lesions.

Long-term clinical outcomes of imiquimod 5% cream vs. diclofenac 3% gel for actinic keratosis on the face or scalp: a pooled analysis of two randomized controlled trials

BACKGROUND

Actinic keratosis (AK) is an early in situ epidermal cancer which can progress to invasive squamous cell carcinoma (SCC). Imiquimod 5% cream (IMIQ) and diclofenac 3% gel (DIC) are frequently used to treat AK; however, their long-term effects following repeated treatment cycles have never been compared.

OBJECTIVE

To compare IMIQ and DIC in the treatment of AK with respect to the risk of change to grade III AK or invasive SCC, after 3 years.

METHODS

Data were pooled from two randomized, active-controlled, open-label, multicentre, multinational, phase IV studies (Clinicaltrials.gov NCT00777127/NCT01453179), with two parallel groups. Studies were conducted between 2008 and 2015 and were almost identical in design. Patients eligible for inclusion were immunocompetent adults with 5-10 visible AK lesions on the face/scalp and grade I/II AK. The primary endpoint was inhibition of histological change to grade III AK or invasive SCC in the study treatment area, observed until month 36. Patients applied either IMIQ or DIC for a maximum of six treatment cycles.

RESULTS

In total, 479 patients (IMIQ 242; DIC 237) were included in the full analysis set. Histological change to grade III AK or invasive SCC was observed until month 36 in 13 (5.4%) patients treated with IMIQ, compared with 26 (11.0%) patients treated with DIC (absolute risk difference -5.6% [95% confidence interval -10.7%, -0.7%]). Time to histological change was greater in the IMIQ group than the DIC group (P = 0.0266). Frequency of progression to invasive SCC was lower with IMIQ than with DIC at all time points. Initial clearance rate was higher in the IMIQ group compared with the DIC group, while recurrence rate was lower. Both treatments were well tolerated.

CONCLUSIONS

Over 3 years, IMIQ was superior to DIC in clearing AK lesions and preventing histological change to grade III AK or invasive SCC and recurrence.

Updates on Treatment Approaches for Cutaneous Field Cancerization

Purpose of Review

Field cancerization describes the phenomenon that multiple heterogenous mutations may arise in an area exposed to chronic carcinogenic stimuli. Advances in the understanding of cutaneous field cancerization have led to novel therapeutic approaches to the management of actinic keratoses (AKs). Herein, we review the literature on the pathophysiology and emerging research of field cancerization in dermatology.

Recent Findings

The classification systems for grading AK lesions are being refined with investigations focusing on their clinical utility. There is a growing shift towards field-directed treatment for AKs as the importance of field cancerization becomes clearer. Current field-directed therapies are being optimized and novel therapeutic modalities are being studied.

Summary

Field cancerization underlies the transformation of photodamaged skin into AKs and potentially cutaneous SCC (cSCC). Clinically meaningful classification systems for AKs are needed to better inform decisions regarding treatment. As we learn more about the role of field characterization in photodamage, AKs and cSCCs, therapeutic strategies are becoming more field-directed rather than lesion-directed.

Modern aspects of photodynamic therapy of actinic keratoses

Currently, photodynamic therapy (PDT) remains the most effective treatment for actinic keratosis (AK). With the increase in the incidence of AK, mainly due to the popularization of recreation in countries with increased insolation, there is an increasing interest in developing new methods of diagnostics and treatment and improving the existing ones. Studies that are aimed at determining the final efficacy of PDT, taking into account the resulting adverse reactions and long-term cosmetic results, are becoming increasingly popular. The nature of the light needed to excite a photosensitizer (PS) opens up new possibilities in the field of experimental studies that are aimed at reducing adverse reactions with similar efficacy of the applied therapy. In the review article, we presented the results of our own and foreign studies on the diagnosis and treatment of AK for 2017–2019, namely: we determined the possibilities of using sources with natural and short-wave radiation at different depths of skin lesions; presented a classification of the growth of AK in the basal layer of the epidermis, which increases the possibility of predicting the outcomes of the disease; showed the prevailing efficiency of fluorescent diagnostics compared with traditional diagnostic methods; evaluated the advantages of PDT using natural light and artificial sources of radiation; described the possibility of using a combination of drugs to increase the effectiveness of PDT in difficult to treat areas and in AK foci with a high degree of damage to the basal layer of the epidermis. 

Scalp ulcers - differential diagnoses that should be sought!

BACKGROUND

Ulceration of the scalp is an uncommon clinical presentation, and it may be caused by myriads of cutaneous etiologies such as infections, inflammatory disorders, and malignancies. We sought to reveal the underlying etiology of scalp ulcers referred to our tertiary wound healing clinic; we would also like to propose a classification for scalp ulcerations.

METHODS

A retrospective study was conducted in an academic tertiary wound healing clinic between January 2015 and June 2018. The study was approved by the Women's College Hospital Institutional Research Ethics Board. We have also conducted a review of the literature to recognize the major causes of scalp ulceration reported in the literature.

RESULTS

We have identified a total number of 15 patients with scalp ulceration. Twelve patients with atypical scalp ulcers underwent a skin biopsy. A malignancy rate of 73% (11/15) was diagnosed histologically. The review of the literature showed 237 articles. After screening the title and the abstracts, we have selected 41 case reports for the full text review.

CONCLUSION

Scalp ulcers are uncommon but important. Our sample study indicates the high frequency of malignant etiologies presenting as scalp ulcers. These results emphasize not only the need for clinicians to be on the watch for the possibility of this option but rather highlights the need for early biopsy to prevent further complications. We hope that our paper helps to shed some light on this topic and guide clinicians on how to approach scalp ulceration.

Somatic mutations in kinetochore gene KNSTRN are associated with basal proliferating actinic keratoses and cutaneous squamous cell carcinoma

BACKGROUND

Mutations in kinetochore gene KNSTRN accelerate the development of cutaneous squamous cell carcinoma (SCC) and may correlate with different histological classifications of actinic keratosis (AKs).

OBJECTIVE

To determine KNSTRN gene mutation frequency in healthy skin (HS), actinically damaged skin (ADS), in AKs with different histomorphological gradings and invasive SCCs.

METHODS

All samples were histologically evaluated. AK lesions were additionally classified according to their upwards (AK I-III) and downwards (PRO I-III) directed growth pattern. Mutation analyses of all samples were performed using the Sanger method.

RESULTS

With one exception, all detected mutations in KNSTRN gene showed an alanine-to-glutamate substitution at codon 40 (p.Ala40Glu). p.Ala40Glu mutation was found in 6.9% (2/29) of HS, in 16.1% (5/31) of ADS, in 18.3% (20/109) of AKs and in 30.0% (9/30) of invasive SCCs. Further stratification of AKs using the common AK classification of Röwert-Huber revealed the p.Ala40Glu mutation in 14.7% (5/43), 13.3% (4/30) and 24.4% (11/45) (AK I, II and III). In contrast, the new PRO classification showed a distribution of 3.6% (1/28) in PRO I, 21.7% (13/60) in PRO II and 28.6% (6/21) in PRO III. Mutation frequency in HS showed significant differences compared to AKs classified as PRO III and invasive SCCs (P < 0.05). In contrast, there were no statistically significant differences between HS and AKs when classified according to Röwert-Huber.

CONCLUSIONS

Recurrent somatic mutation p.Ala40Glu in KNSTRN gene is associated with basal proliferating AKs in accordance with invasive SCCs. This supports the impact of basal proliferative pattern in terms of progression.

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).

T-Cadherin Expression in Actinic Keratosis Transforming to Invasive Squamous Cell Carcinoma

BACKGROUND/AIMS

Clinical and histological features of actinic keratosis (AK) cannot predict malignant transformation to invasive squamous cell carcinoma (iSCC) in individual lesions. We investigated whether patterns/distribution of T-cadherin in AK lesions have biomarker value in predicting transformation to iSCC.

METHODS

28 specimens of cutaneous iSCC exhibiting adjacent or overlying AK were immunostained for T-cadherin and classified according to AK histological grade (AK I-III) and basal growth pattern (PRO I-III).

RESULTS

T-cadherin staining was absent/very weak in 16 and strongly positive in 12 cases. iSSCs lacking T-cadherin expression were most commonly (12/16 cases) associated with type AK I or PRO I lesions, whereas the majority (10/12 cases) of T-cadherin-positive iSCCs originated from AK II and AK III/PRO II and PRO III. In T-cadherin-negative iSCCs, T-cadherin expression was absent in overlying AK and early invasive tumour but retained in AK areas adjacent to the tumour. In contrast, T-cadherin-positive iSCCs displayed expression of T-cadherin in the adjacent AK and early invasive tumour.

CONCLUSION

T-cadherin-negative iSCC arises from AK showing partial or extensive regional loss of T-cadherin in the basal layer of the epidermis. We speculate that T-cadherin loss in individual AK lesions could indicate potential transformation of AK into aggressive iSCC.

Daylight photodynamic therapy for field cancerization: lessons from molecular biology

Actinic keratoses (AKs) represent in-situ squamous cell carcinomas that potentially invade subepidermal structures and may metastasize. Until now, it is unpredictable to determine which AK lesions show this aggressive behavior. As AKs usually occur in large sun exposed areas, field-directed treatments have become the standard treatment regimen. Among these, conventional photodynamic therapy (cPDT) with 5-aminolaevulinic acid (ALA) or methyl-aminolevulinate (MAL) using red light is particularly effective in the treatment of AKs, but acceptance of the therapy is impaired by severe pain during treatment. Daylight PDT (dPDT) has demonstrated to be an equally effective alternative treatment option which is less painful. Recent attempts to determine the risk of AKs that demonstrate particular aggressive biological behavior by implementation of clinical and histological characteristics of AKs have not lead to conclusive results. Therefore, a look at the molecular biology of AKs could serve as a useful tool to develop a risk profiling for separation of those patients that are of particular risk to develop invasive tumor and, by this, to facilitate a more effective and adapted treatment option.