Noninvasive diagnostic tools for nonmelanoma skin cancer

Photographic scale for the characterization of actinic keratosis through reflectance confocal microscopy: a quantitative approach to cellular transformation

Background

Actinic keratosis (AK) is a highly prevalent pre-cancerous skin lesion that often leads to cutaneous squamous cell carcinoma. There are different stages of evolution of the disease and several features that characterize keratosis. This study aimed to develop a qualitative and quantitative visual diagnostic tool to facilitate the identification of the characteristics and severity of the main cellular attributes of AK and to show its applicability in evaluating the evolution or treatment through image analysis.

Methods

Literature research on the main scientific databases and in the institute's database was carried out to gather all the different levels of cellular transformation. To validate the scale, a preliminary characterization study was carried out with 21 subjects who had clinically diagnosed AK lesions to classify the attributes in each skin layer and test the accuracy of the diagnosis of the scale. Afterward, and to show the possibility of a follow-up with a topical treatment, the subjects were divided into two treatment groups, receiving either a cream formulation containing retinoic acid, or a placebo formula. The evaluation was carried out through confocal reflectance microscopy and a digital camera with dermoscopic quality before and after 90 days of treatment.

Results

A table detailing the 18 attributes of AK, and a photographic scale containing RCM images graded by scores established for each characteristic and the frequency of spreading were developed. The results of the validation presented good repeatability, correlation with clinical evaluation, and capacity for differentiating treatments demonstrated by the significant improvement after topical treatment by the reduction of the score for 10 out of the 18 attributes. The preliminary study, evaluated by the detailed transformation scale highlights important differences in the subclinical approach that allows a deeper evaluation of the aspects of the lesion's re-incidence even after fully treated skin sites.

Conclusion

This study brings an innovative method based on RCM, to assist in the quantification of cell transformation level, provide early diagnosis, and deliver a powerful treatment evaluation tool to provide smoother treatment, as well as prevent re-incidence in the cases.

An Update on Non-Invasive Skin Imaging Techniques in Actinic Keratosis-A Narrative Review

Nonmelanocytic skin cancers (NMSCs) are currently the most common group of human cancers and include all tumors that are not melanomas. Increased exposure to sunlight over the past few years, the lack of regular and proper use of sunscreen, the aging of the population, and better screening techniques are the reasons for the escalation in their diagnosis. Squamous cell carcinoma (SCC) comprises nearly 37% of the tumors in this group and can originate from actinic keratosis (AK), which usually presents as pink, often scaly plaques, usually located on the face or scalp. Advances in dermatoscopy, as well as the development of other non-invasive skin imaging modalities such as high-frequency ultrasound (HFUS), reflectance confocal microscopy (RCM), and optical coherence tomography (OCT), have allowed for greatly increased sensitivity in diagnosing these lesions and monitoring their treatment. Since AK therapy is usually local, and SCCs must be removed surgically, non-invasive imaging methods enable to correctly qualify difficult lesions. This is especially important given that they are very often located on the face, and achieving an appropriate cosmetic result after treatments in this area is very important for the patients. In this review, the authors describe the use of non-invasive skin imaging methods in the diagnosis of actinic keratosis.

Digitally Enhanced Methods for the Diagnosis and Monitoring of Treatment Responses in Actinic Keratoses: A New Avenue in Personalized Skin Care

Non-melanocytic skin cancers represent an important public health problem due to the increasing incidence and the important local destructive potential. Thus, the early diagnosis and treatment of precancerous lesions (actinic keratoses) is a priority for the dermatologist. In recent years, non-invasive skin imaging methods have seen an important development, moving from simple observational methods used in clinical research, to true diagnostic and treatment methods that make the dermatologist's life easier. Given the frequency of these precancerous lesions, their location on photo-exposed areas, as well as the long treatment periods, with variable, imprecise end-points, the need to use non-invasive imaging devices is increasingly evident to complete the clinical observations in the diagnosis and treatment of these lesions, with the aim of increasing accuracy and decreasing the adverse effects due to long treatment duration. This is the first review that brings together all skin imaging methods (dermoscopy, reflectance confocal microscopy, ultrasonography, dermoscopy-guided high frequency ultrasonography, and optical coherence tomography) used in the evaluation of actinic keratoses and their response to different treatment regimens.

Update on Management Recommendations for Advanced Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer, the incidence of which has risen over the last years. Although cSCC rarely metastasizes, early detection and treatment of primary tumours are critical to limit progression and local invasion. Several prognostic factors related to patients' clinicopathologic profile and tumour features have been identified as high-risk markers and included in the stratification scales, but their association with regional control or survival is uncertain. Therefore, decision-making on the diagnosis and management of cSCC should be made based on each individual patient's characteristics. Recent advances in non-invasive imaging techniques and molecular testing have enhanced clinical diagnostic accuracy. Surgical excision is the mainstay of local treatment, whereas radiotherapy (RT) is recommended for patients with inoperable disease or in specific circumstances. Novel systemic treatments including immunotherapies and targeted therapies have changed the therapeutic landscape for cSCC. The anti-PD-1 agent cemiplimab is currently the only FDA/EMA-approved first-line therapy for patients with locally advanced or metastatic cSCC who are not candidates for curative surgery or RT. Given the likelihood of recurrence and the increased risk of developing multiple cSCC, close follow-up should be performed during the first years of treatment and continued long-term surveillance is warranted.

Squamous cell carcinoma: 2021 updated review of treatment

Squamous cell carcinoma is the second most common cutaneous malignancy, requiring early diagnosis to prevent metastasis. Updated guidelines in the definition of clinical features, diagnostic modalities, grading, staging, surgical, and nonsurgical treatment methods are necessary. Diagnostic methods from biopsy, dermoscopy, and reflectance confocal microscopy have improved to include high-frequency ultrasonography, optical coherence tomography, and computed tomography. Non-surgical treatment methods include topical therapy, cryosurgery, photodynamic therapy, and radiation. Surgical treatment methods include surgical excision with margins and Mohs surgery. Clinical trials encourage further research to address the knowledge base of genetic variations and lymph node metastasis.

Basic Quality Controls Used in Skin Tissue Engineering

Reconstruction of skin defects is often a challenging effort due to the currently limited reconstructive options. In this sense, tissue engineering has emerged as a possible alternative to replace or repair diseased or damaged tissues from the patient's own cells. A substantial number of tissue-engineered skin substitutes (TESSs) have been conceived and evaluated in vitro and in vivo showing promising results in the preclinical stage. However, only a few constructs have been used in the clinic. The lack of standardization in evaluation methods employed may in part be responsible for this discrepancy. This review covers the most well-known and up-to-date methods for evaluating the optimization of new TESSs and orientative guidelines for the evaluation of TESSs are proposed.

1.7-Micron Optical Coherence Tomography Angiography for Characterization of Skin Lesions-A Feasibility Study

Optical coherence tomography (OCT) is a non-invasive diagnostic method that offers real-time visualization of the layered architecture of the skin in vivo. The 1.7-micron OCT system has been applied in cardiology, gynecology and dermatology, demonstrating an improved penetration depth in contrast to conventional 1.3-micron OCT. To further extend the capability, we developed a 1.7-micron OCT/OCT angiography (OCTA) system that allows for visualization of both morphology and microvasculature in the deeper layers of the skin. Using this imaging system, we imaged human skin with different benign lesions and described the corresponding features of both structure and vasculature. The significantly improved imaging depth and additional functional information suggest that the 1.7-micron OCTA system has great potential to advance both dermatological clinical and research settings for characterization of benign and cancerous skin lesions.

Optical coherence tomography-based non-invasive evaluation of premalignant lesions in SKH-1 mice

Non-invasively diagnosis of actinic keratoses (AK) is important for preventing cutaneous squamous cell carcinoma (cSCC). Optical coherence tomography (OCT) can be used to detect the cross-sectional skin micromorphology with sufficient resolution and imaging depth. It has the capability to reveal the changes in skin microstructure during the development of AK. Therefore, OCT can serve as a tool for diagnosing AK. This study explores the feasibility of OCT in evaluating the structural changes in mouse skin at the different stages following exposure to ultraviolet radiation. The performance of OCT is compared with histology, the gold standard in this context. The imaging results demonstrate that a wave-shaped irregular dermo-epidermal junction (DEJ), as well as the continuous thickening of the epidermis, are useful diagnostic parameters for diagnosing AK. Histological examinations confirm these observations. These findings emphasize the need for effective skin protection or medical treatment once changes in the DEJ and epidermis are detected. OCT shows strong potential for non-invasive evaluation of such changes and AK development, and can be used for the prevention of cSCC without the necessity of taking biopsies.

Pathogenesis of Keratinocyte Carcinomas and the Therapeutic Potential of Medicinal Plants and Phytochemicals

Keratinocyte carcinoma (KC) is a form of skin cancer that develops in keratinocytes, which are the predominant cells present in the epidermis layer of the skin. Keratinocyte carcinoma comprises two sub-types, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). This review provides a holistic literature assessment of the origin, diagnosis methods, contributing factors, and current topical treatments of KC. Additionally, it explores the increase in KC cases that occurred globally over the past ten years. One of the principal concepts highlighted in this article is the adverse effects linked to conventional treatment methods of KC and how novel treatment strategies that combine phytochemistry and transdermal drug delivery systems offer an alternative approach for treatment. However, more in vitro and in vivo studies are required to fully assess the efficacy, mechanism of action, and safety profile of these phytochemical based transdermal chemotherapeutics.

Use of digital photography to identify neoplastic skin lesions after labelling by ALA-derived protoporphyrin

Actinic keratosis is a premalignant skin lesion that develops into non-melanoma skin cancer. Various imaging techniques have been developed to find the actinic keratosis lesion. In this clinical study, the feasibility of a nonspectroscopic fluorescence imaging system is investigated for spatial assessment of the actinic keratosis lesion. Six patients between the ages of 70 and 80 years old are diagnosed with actinic keratosis by a board-certified dermatologist to obtain biopsy-proven clinical images. The patients were treated with 5-aminolevulinic acid, which is transformed into the protoporphyrin IX. After illuminating ultraviolet-A light on facial lesions, the protoporphyrin IX produces the exogenous fluorescence. The fluorescence is measured using both a hyperspectral camera and an RGB color camera to obtain spectroscopic and nonspectroscopic fluorescence images, respectively. It is found that fluorescence intensity of the actinic keratosis lesion is higher than that of normal skin. Based on combined fluorescence and physiological characteristics, the actinic keratosis lesion is distinguished from the adjacent normal skin area. For delineation of the actinic keratosis lesion, a linear unmixing algorithm is applied to spectroscopic image data and an erythema index is calculated from nonspectroscopic image data. Then, two extracted actinic keratosis lesions are compared for cross-validation. As a result, both spectroscopic and nonspectroscopic fluorescence images demarcate an identical lesion of actinic keratosis. Given the affordability and simplicity, an RGB camera and a 5-ALA photosensitizer can be used as a cost-effective nonspectroscopic imaging modality for accurate assessment of actinic keratosis margins.

Analysis of the effectiveness of chemical peelings in the treatment of acne vulgaris assessed using high-frequency ultrasound-A comparative study

BACKGROUND

The use of high-frequency ultrasound for noninvasive assessment of skin during chemical peeling therapies may be a useful tool.

AIMS

To determine whether high-frequency ultrasound is a useful tool to noninvasive assessment of skin and evaluation therapy progress.

PATIENTS/METHODS

The 14 women underwent four treatments with chemical peelings at 2-week intervals. Before, after 4 weeks and after 9 weeks, photographic documentation and scans were recorded using a high-resolution ultrasound system.

RESULTS

As a result of applying pyruvic acid peeling, the thickness of the entrance echo on the forehead, cheek, and chin was reduced. After applying the peeling consisting of a mixture of glycolic and salicylic acids, the thickness of the entrance echo of the epidermis decreased on the forehead, cheek, and chin. As a result of applying a 50% pyruvic acid peeling, the density of dermis on the forehead, cheeks, and chin increased. A similar increase in the density of dermis was observed on the forehead, cheeks, and chin after applying a mixture of glycolic and salicylic acid.

CONCLUSION

High-frequency ultrasound is a useful tool for monitoring the progress in the treatment of acne vulgaris using chemical peelings.

Squamous Cell Carcinoma: An Update on Diagnosis and Treatment

Squamous cell carcinoma (SCC) accounts for most nonmelanoma skin cancer-related metastatic disease and deaths. Histopathology and correct surgical excision remain the gold standard for the diagnosis and treatment of SCC; however, new diagnostic imaging techniques such as dermoscopy and reflectance confocal microscopy have increased the diagnostic accuracy in terms of early recognition, better differential diagnosis, more precise selection of areas to biopsy, and noninvasive monitoring of treatments. The therapeutic intervention in patients with severe actinic damage and multiple in situ/low-risk SCC, and the development of innovative treatments such as epidermal growth factor receptor inhibitors and immune checkpoint inhibitors for locally advanced and metastatic SCC, are improving considerably the approach to the disease. This review summarizes the up-to-date knowledge in the field of detection, treatment, and monitoring of cutaneous SCC.

The actinic dysplasia syndrome - diagnostic approaches defining a new concept in field carcinogenesis with multiple cSCC

Usually, SCC lesions are surrounded by a number of clinically visible and non-visible (subclinical) areas of actinically damaged skin containing cells with dysplasia, and thus may be designated actinic dysplasia syndrome. The epithelial damage is caused mainly by UV radiation, inducing mutations in keratinocytes that may confer growth advantages resulting in preneoplastic fields. The development of visible dysplastic lesions (actinic keratosis - AK) and subsequent progression to invasive SCC requires further mutations in cancer-associated genes, like tumour suppressor genes and cell cycle regulators. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) represent a considerable advantage for the investigation of field cancerization. In addition, imaging allows the non-invasive monitoring of topical treatments for AKs. RCM provides in vivo horizontal skin sections with a high, 1-μm lateral resolution (similar to histopathology) but with a limited penetration (about 200 μm), which can hamper the visualization of important areas such as the dermal-epidermal junction. Conventional OCT has better penetration (1-2 mm) at the expense of a more limited resolution (much lower than histopathology). Line-field confocal OCT (LC-OCT) combines the high precision of RCM and the good penetration of OCT in a single device and therefore appears to be very useful in diagnosing/managing AKs.

Review of Modern Techniques for the Assessment of Skin Hydration

Skin hydration is a complex process that influences the physical and mechanical properties of skin. Various technologies have emerged over the years to assess this parameter, with the current standard being electrical probe-based instruments. Nevertheless, their inability to provide detailed information has prompted the use of sophisticated spectroscopic and imaging methodologies, which are capable of in-depth skin analysis that includes structural and composition details. Modern imaging and spectroscopic techniques have transformed skin research in the dermatological and cosmetics disciplines, and are now commonly employed in conjunction with traditional methods for comprehensive assessment of both healthy and pathological skin. This article reviews current techniques employed in measuring skin hydration, and gives an account on their principle of operation and applications in skin-related research.

A review of non-invasive imaging in extramammary Paget's disease

Extramammary Paget's Disease (EMPD) is a rare intraepithelial adenocarcinoma that classically manifests with pruritic, erythematous and scaling plaques. The clinical picture frequently mimics inflammatory or infectious conditions and is thus commonly misdiagnosed. The assessment of tumour margins is equally challenging as tumours have a propensity to spread beyond clinically visible boundaries. Appropriate non-invasive diagnostic tools can assist in the early detection, diagnosis and management of EMPD. This paper will review the literature on non-invasive imaging modalities used in EMPD. Articles from the PubMed database were selected based on relevance to the topic of this review. Articles that were not specific to EMPD and non-invasive imaging were excluded. Search strategy is further described in the methods section below. Eighteen articles were selected for this review: six PET/CT, five reflectance confocal microscopy (RCM), two photodynamic diagnosis (PDD), two dermoscopy, two MRI and one optical coherence tomography (OCT) paper(s). Dermoscopy, PDD, RCM and OCT can help to distinguish malignant conditions, including EMPD, from benign conditions. RCM and OCT can identify atypical cells in real-time, and have the potential to improve the accuracy of surgical margins intraoperatively and overall management. Distinctive confocal characteristics of EMPD have been described using RCM. The sensitivity and specificity of these findings require additional validation. Radiographic techniques also play a central role in the diagnosis of EMPD and assessment of disease spread. PET/CT and MRI can detect primary disease, nodal and distant metastases, with superior delineation of disease spread on MRI. Limitations of PET/CT are mainly related to primary tumour thickness, and size and FDG-avidity of nodal and distant metastases. Limitations of MRI include the fact that few studies have examined its use in EMPD; additional research is warranted. Randomized controlled trials and large prospective studies evaluating the use of non-invasive imaging in EMPD are needed.

Seborrheic keratoses mimicking melanoma unveiled by in vivo reflectance confocal microscopy

BACKGROUND

Seborrheic keratoses (SebK) with atypical dermoscopy presentation are increasingly reported. These lesions do not exhibit typical dermoscopy features of SebK and sometimes mimic melanoma, thus complicating the differential diagnosis. Reflectance confocal microscopy (RCM) is a non-invasive tool, which allows an in vivo imaging of the skin. The study objectives were to evaluate the agreement between RCM classification and histological diagnoses, and the reliability of well-known RCM criteria for SebK in the identification of SebK with atypical dermoscopy presentation.

MATERIALS AND METHODS

We retrospectively analysed at RCM excised lesions presenting in dermoscopy ≥1 score at revisited 7-point checklist. The study population consisted of cases showing no melanocytic RCM findings. Lesions were investigated for distinct non-melanocytic RCM features, blinded from histopathology diagnoses. Histopathology matching was then performed before statistical analysis.

RESULTS

The study consisted of 117 cases, classified at RCM as SebK (71 cases), dermatofibroma (18 cases), basal cell carcinoma (13 cases), squamous cell carcinoma (2 cases), and "non-specific" (13 cases). Overall K strength of agreement at histopathology matching proved 0.76. Of the 71 cases classified at RCM with SebK, agreement was achieved in 97%.

CONCLUSION

Reflectance confocal microscopy classification proved high agreement with histopathology for SebK with atypical dermoscopy presentations, allowing an early differential diagnosis. RCM features in this group of lesions were similar to those described for typical cases of SebK, and may assist clinician therapy decision making, whilst avoiding unnecessary excisions.

Actinic Keratosis and Non-Invasive Diagnostic Techniques: An Update

Actinic keratosis represents the earliest manifestation of non-melanoma skin cancer. Because of their risk of progression to invasive squamous cell carcinoma, an earlier diagnosis and treatment are mandatory. Their diagnosis sometimes could represent a challenge even for expert dermatologists. Dermoscopy, confocal laser microscopy and optical coherence tomography could help clinicians in diagnosis.

High frequency ultrasound with color Doppler in dermatology

Ultrasonography is a method of imaging that classically is used in dermatology to study changes in the hypoderma, as nodules and infectious and inflammatory processes. The introduction of high frequency and resolution equipments enabled the observation of superficial structures, allowing differentiation between skin layers and providing details for the analysis of the skin and its appendages. This paper aims to review the basic principles of high frequency ultrasound and its applications in different areas of dermatology.

Accuracy of optical coherence tomography for the diagnosis of superficial basal cell carcinoma: a prospective, consecutive, cohort study of 168 cases

BACKGROUND

Superficial basal cell carcinoma (sBCC) can be safely treated topically. Potentially noninvasive imaging techniques, such as optical coherence tomography (OCT), may be useful to diagnose and manage patients with sBCC and obviate the need for biopsy.

OBJECTIVES

To evaluate in OCT (i) the sensitivity and specificity for sBCC diagnosis, (ii) the accuracy in determining BCC depth and (iii) the role in management of sBCC mimickers.

METHODS

A prospective, consecutive cohort of lesions for which sBCC was considered in the differential diagnosis. These lesions underwent clinical, dermoscopic and OCT assessment. Diagnosis and its confidence were recorded for each modality and were correlated with the histopathological diagnosis (punch biopsy). Interpretation of the OCT images and assessment of individual features were performed blinded to the biopsy results.

RESULTS

In total, 168 lesions were recruited: 52% were sBCC, 26% were other BCC variants and the remaining lesions were actinic keratosis, squamous cell carcinoma in situ, other benign inflammatory processes and two other malignant tumours. The sensitivity and specificity of OCT for diagnosis of sBCC were 0·87 and 0·80, respectively. There was excellent correlation between OCT and biopsy for tumour depth amongst tumours ≤ 0·4 mm (Pearson correlation r = 0·86, P < 0·001), but the correlation was less as depth increased (Pearson correlation r = 0·71, P < 0·001 for all tumours < 1·0 mm).

CONCLUSIONS

OCT has good diagnostic accuracy for diagnosing sBCC and measuring depth in tumours ≤ 0·4 mm. Potentially OCT can reduce the need for biopsy in clinically suspected sBCCs. However, careful follow-up is required in such cases as there is a small risk (5%) of misdiagnosis.

Morphologic features of basal cell carcinoma using the en-face mode in frequency domain optical coherence tomography

BACKGROUND

Optical coherence tomography (OCT) has become a valuable non-invasive tool in the in vivo diagnosis of non-melanoma skin cancer, especially of basal cell carcinoma (BCC). Due to an updated software-supported algorithm, a new en-face mode - similar to the horizontal en-face mode in high-definition OCT and reflectance confocal microscopy - surface-parallel imaging is possible which, in combination with the established slice mode of frequency domain (FD-)OCT, may offer additional information in the diagnosis of BCC.

OBJECTIVES

To define characteristic morphologic features of BCC using the new en-face mode in addition to the conventional cross-sectional imaging mode for three-dimensional imaging of BCC in FD-OCT.

METHODS

A total of 33 BCC were examined preoperatively by imaging in en-face mode as well as cross-sectional mode in FD-OCT. Characteristic features were evaluated and correlated with histopathology findings.

RESULTS

Features established in the cross-sectional imaging mode as well as additional features were present in the en-face mode of FD-OCT: lobulated structures (100%), dark peritumoral rim (75%), bright peritumoral stroma (96%), branching vessels (90%), compressed fibrous bundles between lobulated nests ('star shaped') (78%), and intranodular small bright dots (51%). These features were also evaluated according to the histopathological subtype. In the en-face mode, the lobulated structures with compressed fibrous bundles of the BCC were more distinct than in the slice mode.

CONCLUSION

FD-OCT with a new depiction for horizontal and vertical imaging modes offers additional information in the diagnosis of BCC, especially in nodular BCC, and enhances the possibility of the evaluation of morphologic tumour features.

Adjunct use of optical coherence tomography increases the detection of recurrent basal cell carcinoma over clinical and dermoscopic examination alone

BACKGROUND

Basal cell carcinoma (BCC) is a locally destructive form of skin cancer, mainly affecting Caucasians. In the last few years non-surgical treatments of BCC have become widely used and non-invasive methods for treatment monitoring and follow-up are therefore becoming increasingly warranted. The objective of this study was to investigate the utility of adjunct use of non-invasive optical coherence tomography (OCT) imaging for the detection of recurrent BCC over clinical and dermoscopic examination alone, in a real-world setting.

METHODS

A total of 58 patients, previously treated with curettage and/or MAL-PDT for BCC, were included in the study. The patients were examined clinically and dermoscopically for recurrence by a dermatologist before joining the study. The included patients were then OCT scanned and if the OCT images raised suspicion of recurrent BCC the area was biopsied.

RESULTS

In 6 cases the clinical examination revealed suspicions recurrent lesions and OCT correctly identified all of these (6/6). In 49 cases the follow-up examinations showed no clinical or dermoscopic signs of recurrence, but in 12.2% (6/49) of these cases the subsequent OCT examination revealed a subclinical recurrent BCC lesion. These were all confirmed by histology. In 3 cases both the clinical and the OCT diagnosis was unclear and recurrent BCC could not be ruled out, but histology showed no sign of malignancy.

CONCLUSIONS

These results suggest that the adjunct use of OCT increases the detection rate of recurrent BCC over clinical/dermoscopy examination alone.

Systematic review of optical coherence tomography usage in the diagnosis and management of basal cell carcinoma

Optical coherence tomography (OCT) is a noninvasive imaging tool used in vivo in real time for diagnosis, treatment delineation and monitoring of basal cell carcinoma (BCC). Features of BCC on OCT have been widely described and reviewed. However, the diagnostic accuracy of OCT in these various applications is unclear. We systematically reviewed the literature to assess the accuracy of OCT in diagnosis and management of BCC using the Embase and Medline databases. In total 179 unique references were identified in the initial search, of which 22 studies with 556 histologically proven BCCs were eligible. Assessment of the quality of eligible studies was undertaken using the STROBE criteria. Data extraction and quality assessment were performed independently by the two authors. This systematic review provides an overview of the clinical applications of OCT in the diagnosis and management of BCC. OCT has been suggested to be useful in the diagnosis, treatment planning and treatment monitoring of BCC. As the technology improves and its utility increases, further studies with good methodological quality will be needed to implement OCT into daily practice.

Grading keratinocyte atypia in actinic keratosis: a correlation of reflectance confocal microscopy and histopathology

BACKGROUND

Actinic Keratosis (AK) is the clinical manifestation of cutaneous dysplasia of epidermal keratinocytes, with progressive trend towards squamous cell carcinoma.

OBJECTIVE

To evaluate the strength of the correlation between keratinocyte atypia, as detected by Reflectance Confocal Microscopy (RCM) and histopathology, and to develop a more objective atypia grading scale for RCM quantification, through a discrete ranking.

METHODS

A total of 48 AKs and two control areas (photodamaged and non-photodamaged skin) were selected for this study. All these areas were documented by RCM and biopsied for histopathology. One representative image of the epidermis was selected for RCM and for histopathology and used for side-by-side comparison with purpose written software. The assessor chose which of two images displayed more keratinocyte atypia, and an ordered list from the image showing the least to the most keratinocyte atypia was generated. Three evaluations were obtained for RCM and two for histopathology.

RESULTS

Good interobserver correlation was obtained for RCM and histopathology grading, with high concordance between RCM and histopathology grading.

CONCLUSIONS

Expert rater scan consistently distinguish different grades of cytological atypia. Non-invasive RCM data from in vivo imaging can be graded for keratinocyte atypia, comparable to histopathological grading.

Combining tape stripping and non-invasive reflectance confocal microscopy : an in vivo model to study skin damage

BACKGROUND

Evaluation of (immuno)histological and cell biological changes in damaged skin requires often an invasive skin biopsy, making in vivo models inappropriate to study skin damage. Reflectance confocal microscopy (RCM) might overcome this limitation. Therefore, we evaluated the use of a tape-stripping model in combination with RCM to provide morphological data on skin damage and recovery.

METHODS

In 25 volunteers, a tape-stripping stimulus was applied. The skin was imaged with RCM during 1 week and 3 mm punch biopsies were obtained.

RESULTS

Strong correlations between epidermal thickness determined by RCM and conventional histological measurements were found. RCM thickness measurements correlated well with epidermal proliferation. The 10× or 15× repeated tape-stripping resulted in skin damage similar to acute stripping. Mild repeated tape-stripping showed no skin damage.

CONCLUSION

Overall, we demonstrated that non-invasive RCM in combination with tape-stripping could be used as model to obtain morphological and cell biological data on skin-material interactions.

Can video thermography improve differential diagnosis and therapy between basal cell carcinoma and actinic keratosis?

Various noninvasive techniques (dermoscopy, confocal microscopy, etc.) have been introduced to help the clinical diagnosis in nonmelanoma skin cancer. Among them, the high definition video thermographic technique (VTG) has recently been proposed. The aim of this study is to define the VTG patterns, respectively of actinic keratosis (AK) and basal cell carcinoma (BCC), and to compare these data with them of dermoscopy. The study included 36 patients with a total number of 135 lesions who underwent clinical, VTG, and dermoscopic examination. The VTG showed the presence of a hyperthermic pattern in all the cases of AK, while in the case of the BCC, the pattern was hypothermic. Dermoscopy also showed distinct pattern for AK and for BCC, but in 22% of them the data were not conclusive. Our study permits us to define two specific VTG patterns, BCC and AK respectively.

Optical coherence tomography: its role in daily dermatological practice

Optical coherence tomography (OCT) is a non-invasive, tomographic imaging technique which generates high-resolution in-vivo images up to mid-dermal layers. Due to continuous technological improvements, OCT is moving from research projects into daily dermatological practice. It can complement other imaging methods like high-frequency ultrasound or confocal microscopy. There is a wide variety of indications for OCT. In addition to aiding in the diagnosis and clinical monitoring of inflammatory dermatoses, OCT is a very useful and feasible technique in dermato-oncology.

The importance of early diagnosis and treatment of actinic keratosis

Chronic, long-term sun exposure results in genetic changes in epidermal keratinocytes and the development of various skin lesions ranging from actinic keratosis (AK) to skin cancer. AK lesions may first appear as rough, scaly spots on sun-exposed skin, and, although most individual AK lesions do not become invasive cancers, the majority of invasive squamous cell carcinomas originate from AK. Genetic analysis demonstrates that ultraviolet radiation-induced mutations and changes in gene expression are present in squamous cell carcinoma, AK, and clinically normal-appearing perilesional sun-exposed skin, which supports the progressive nature of keratinocyte transformation. The presence of certain clinical features, such as large size, ulceration, or bleeding, suggests an increased risk of disease progression. The risk is also increased by evidence of extensive solar damage, advanced age, and immunosuppression. Early diagnosis and consideration for treatment are indicated to clear actinically damaged sites and diminish the risk of invasive squamous cell carcinoma.

High-definition optical coherence tomography enables visualization of individual cells in healthy skin: comparison to reflectance confocal microscopy

High-definition OCT (HD-OCT) is an innovative technique based on the principle of conventional OCT. Our objective was to test the resolution and image quality of HD-OCT in comparison with reflectance confocal microscopy (RCM) of healthy skin. Firstly, images have been made of a ultra-high-resolution line-pair phantome with both systems. Secondly, we investigated 21 healthy volunteers of different phototypes with HD-OCT and RCM on volar forearm and compared the generated images. HD-OCT displays also differences depending on the skin phototype and anatomical site. The 3-μm lateral resolution of the HD-OCT could be confirmed by the phantom analysis. The identification of cells in the epidermis can be made by both techniques. RCM offers the best lateral resolution, and HD-OCT has the best penetration depth, providing images of individual cells deeper within the dermis. Eccrine ducts and hair shafts with pilosebaceous units can be observed depending on skin site. HD-OCT provides morphological imaging with sufficient resolution and penetration depth to permit visualization of individual cells at up to 570 μm in depth offering the possibility of additional structural information complementary to that of RCM. HD-OCT further has the possibility for rapid three-dimensional imaging.

Confocal laser scanning microscopy as a new valuable tool in the diagnosis of onychomycosis - comparison of six diagnostic methods

Onychomycosis is common and can mimic several different nail disorders. Accurate diagnosis is essential to choose the optimum antifungal therapy. The aim of this study was to evaluate the use of confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT) as new non-invasive diagnostic tools in onychomycosis and to compare them with the established techniques. In a prospective trial, 50 patients with suspected onychomycosis and 10 controls were examined by CLSM and OCT. Parallel KOH preparation, culture, PAS-staining and PCR were performed. PCR showed the highest sensitivity, followed by CLSM, PAS and KOH preparation. OCT offered the second best sensitivity but displayed the lowest specificity. CLSM and KOH preparation showed a high specificity and CLSM offered the best positive predictive value, similar to KOH preparation and OCT. Fungal culture showed the lowest sensitivity and the worst negative predictive value, yet culture and PCR are the only techniques able to identify genus and species. In summary, CLSM was comparable to PAS staining and superior to KOH preparation. Due to the low specificity we assess OCT not as appropriate. In the differentiation of species PCR outplays the fungal culture in terms of time and sensitivity.

In vivo investigations on the penetration of various oils and their influence on the skin barrier

BACKGROUND

The skin represents a potent barrier to the environment, which can be enhanced by the topical application of skin care products, such as oil and oil-based formulations by moisturizing the skin.

METHODS

The aim of this study was the investigation of the penetration behaviour of four vegetable oils and of paraffin oil into the stratum corneum by laser scanning microscopy. In addition, the occlusion capacity of these substances was assessed by transepidermal water loss (TEWL) measurements. Petrolatum served as a positive control for skin occlusion. The study was conducted in vivo and included six healthy volunteers.

RESULTS

Paraffin oil, as well as the vegetable oils, penetrated only into the first upper layers of the stratum corneum. TEWL measurements indicated that the application of the vegetable oils (except jojoba oil) as well as paraffin oil, led to a similar occlusion of the skin surface. The most effective occlusion was found for petrolatum.

CONCLUSION

For the investigated oils, a deeper penetration than into the first upper layers of the stratum corneum could be excluded. The decreased TEWL values indicate that the application of the oils leads to a semi-occlusion of the skin surface as it is intended by the use of oils to retain moisture in skin.

Intradermal indocyanine green for in vivo fluorescence laser scanning microscopy of human skin: a pilot study

Background

In clinical diagnostics, as well as in routine dermatology, the increased need for non-invasive diagnosis is currently satisfied by reflectance laser scanning microscopy. However, this technique has some limitations as it relies solely on differences in the reflection properties of epidermal and dermal structures. To date, the superior method of fluorescence laser scanning microscopy is not generally applied in dermatology and predominantly restricted to fluorescein as fluorescent tracer, which has a number of limitations. Therefore, we searched for an alternative fluorophore matching a novel skin imaging device to advance this promising diagnostic approach.

Methodology/Principal Findings

Using a Vivascope®-1500 Multilaser microscope, we found that the fluorophore Indocyanine-Green (ICG) is well suited as a fluorescent marker for skin imaging in vivo after intradermal injection. ICG is one of few fluorescent dyes approved for use in humans. Its fluorescence properties are compatible with the application of a near-infrared laser, which penetrates deeper into the tissue than the standard 488 nm laser for fluorescein. ICG-fluorescence turned out to be much more stable than fluorescein in vivo, persisting for more than 48 hours without significant photobleaching whereas fluorescein fades within 2 hours. The well-defined intercellular staining pattern of ICG allows automated cell-recognition algorithms, which we accomplished with the free software CellProfiler, providing the possibility of quantitative high-content imaging. Furthermore, we demonstrate the superiority of ICG-based fluorescence microscopy for selected skin pathologies, including dermal nevi, irritant contact dermatitis and necrotic skin.

Conclusions/Significance

Our results introduce a novel in vivo skin imaging technique using ICG, which delivers a stable intercellular fluorescence signal ideal for morphological assessment down to sub-cellular detail. The application of ICG in combination with the near infrared laser opens new ways for minimal-invasive diagnosis and monitoring of skin disorders.