Diagnosis of nonmelanoma skin cancer/keratinocyte carcinoma: a review of diagnostic accuracy of nonmelanoma skin cancer diagnostic tests and technologies

Seeing beyond skin deep: High-resolution ultrasound in dermatology-A comprehensive review and future prospects

High-resolution ultrasound (HRUS), operating at frequencies of 20-25 MHz, is a non-invasive imaging tool that offers dermatologists the ability to visualize structures beneath the skin surface. The objective of this review is to present a comprehensive overview of HRUS applications, emphasising its utility in diagnosing, characterising and managing various dermatological conditions. We undertook a comprehensive literature review on the dermatological application of HRUS across Medline, Embase and Cochrane Library databases, while also incorporating our own clinical experience of over 16 years with the tool. In normal skin, the epidermis and dermis are hyperechoic, and the subcutaneous layer is hypoechoic. Basal cell carcinomas appear hypoechoic with irregular margins, while the presence of hyperechoic inclusion bodies suggests aggressive pathology. Squamous cell carcinomas pose challenges due to acoustic shadow artefacts from the thickened stratum corneum. Melanomas are homogenous hypoechoic lesions, with HRUS used to accurately predict Breslow thickness. HRUS provides dermatologists with a valuable adjunct to traditional clinical examination. Future advancement in image resolution and the standardisation of diagnostic parameters may further expand its utility.

High-fidelity detection, subtyping, and localization of five skin neoplasms using supervised and semi-supervised learning

Background

Skin cancers are the most common malignancies diagnosed worldwide. While the early detection and treatment of pre-cancerous and cancerous skin lesions can dramatically improve outcomes, factors such as a global shortage of pathologists, increased workloads, and high rates of diagnostic discordance underscore the need for techniques that improve pathology workflows. Although AI models are now being used to classify lesions from whole slide images (WSIs), diagnostic performance rarely surpasses that of expert pathologists.

Objectives

The objective of the present study was to create an AI model to detect and classify skin lesions with a higher degree of sensitivity than previously demonstrated, with potential to match and eventually surpass expert pathologists to improve clinical workflows.

Methods

We combined supervised learning (SL) with semi-supervised learning (SSL) to produce an end-to-end multi-level skin detection system that not only detects 5 main types of skin lesions with high sensitivity and specificity, but also subtypes, localizes, and provides margin status to evaluate the proximity of the lesion to non-epidermal margins. The Supervised Training Subset consisted of 2188 random WSIs collected by the PathologyWatch (PW) laboratory between 2013 and 2018, while the Weakly Supervised Subset consisted of 5161 WSIs from daily case specimens. The Validation Set consisted of 250 curated daily case WSIs obtained from the PW tissue archives and included 50 "mimickers". The Testing Set (3821 WSIs) was composed of non-curated daily case specimens collected from July 20, 2021 to August 20, 2021 from PW laboratories.

Results

The performance characteristics of our AI model (i.e., Mihm) were assessed retrospectively by running the Testing Set through the Mihm Evaluation Pipeline. Our results show that the sensitivity of Mihm in classifying melanocytic lesions, basal cell carcinoma, and atypical squamous lesions, verruca vulgaris, and seborrheic keratosis was 98.91% (95% CI: 98.27%, 99.55%), 97.24% (95% CI: 96.15%, 98.33%), 95.26% (95% CI: 93.79%, 96.73%), 93.50% (95% CI: 89.14%, 97.86%), and 86.91% (95% CI: 82.13%, 91.69%), respectively. Additionally, our multi-level (i.e., patch-level, ROI-level, and WSI-level) detection algorithm includes a qualitative feature that subtypes lesions, an AI overlay in the front-end digital display that localizes diagnostic ROIs, and reports on margin status by detecting overlap between lesions and non-epidermal tissue margins.

Conclusions

Our AI model, developed in collaboration with dermatopathologists, detects 5 skin lesion types with higher sensitivity than previously published AI models, and provides end users with information such as subtyping, localization, and margin status in a front-end digital display. Our end-to-end system has the potential to improve pathology workflows by increasing diagnostic accuracy, expediting the course of patient care, and ultimately improving patient outcomes.

Reverse Iontophoretic Extraction of Skin Cancer-Related Biomarkers

Non-invasive methods for early diagnosis of skin cancer are highly valued. One possible approach is to monitor relevant biomarkers such as tryptophan (Trp) and kynurenine (Kyn), on the skin surface. The primary aim of this in vitro investigation was, therefore, to examine whether reverse iontophoresis (RI) can enhance the extraction of Trp and Kyn, and to demonstrate how the Trp/Kyn ratio acquired from the skin surface reflects that in the epidermal tissue. The study also explored whether the pH of the receiver medium impacted on extraction efficiency, and assessed the suitability of a bicontinuous cubic liquid crystal as an alternative to a simple buffer solution for this purpose. RI substantially enhanced the extraction of Trp and Kyn, in particular towards the cathode. The Trp/Kyn ratio obtained on the surface matched that in the viable skin. Increasing the receiver solution pH from 4 to 9 improved extraction of both analytes, but did not significantly change the Trp/Kyn ratio. RI extraction of Trp and Kyn into the cubic liquid crystal was comparable to that achieved with simple aqueous receiver solutions. We conclude that RI offers a potential for non-invasive sampling of low-molecular weight biomarkers and further investigations in vivo are therefore warranted.

Bedside Differentiation Between Benign and Malignant Pigmented Skin Tumours by Four Diagnostic Imaging Technologies - A Pilot Study

Fast diagnosis of suspicious pigmented skin lesions is imperative, but current bedside skin imaging technologies are either limited in penetration depth or resolution. Combining imaging methods is therefore highly relevant for skin cancer diagnostics. This pilot study evaluates the ability of optical coherence tomography, reflectance confocal microscopy, photoacoustic imaging and high-frequency ultrasound to differentiate malignant from benign pigmented skin lesions. A total of 41 pigmented skin tumours were scanned prior to excision. Morphologic features and blood vessel characteristics were analysed in reflectance confocal microscopy, optical coherence tomography, high-frequency ultrasound and photoacoustic imaging images and diagnostic accuracy assessed. Three novel photoacoustic imaging features, 7 reflectance confocal microscopy features and two optical coherence tomography features were detected with a high correlation to malignancy, diagnostic accuracy > 71%. No significant features were found in high-frequency ultrasound. Conclusively, optical coherence tomography, reflectance confocal microscopy and photoacoustic imaging in combination enables image-guided evaluation of suspicious pigmented skin tumours at the bedside. Combining these advanced techniques may help to diagnose skin cancer more efficiently.

Characterization of the Biomechanical Properties of Skin Using Vibrational Optical Coherence Tomography: Do Changes in the Biomechanical Properties of Skin Stroma Reflect Structural Changes in the Extracellular Matrix of Cancerous Lesions?

Early detection of skin cancer is of critical importance since the five-year survival rate for early detected skin malignancies is 99% but drops to 27% for cancer that has spread to distant lymph nodes and other organs. Over 2.5 million benign skin biopsies (55% of the total) are performed each year in the US at an alarming cost of USD ~2.5 B. Therefore there is an unmet need for novel non-invasive diagnostic approaches to better differentiate between cancerous and non-cancerous lesions, especially in cases when there is a legitimate doubt that a biopsy may be required. The purpose of this study is to determine whether the differences in the extracellular matrices among normal skin, actinic keratosis (AK), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) can be assessed non-invasively using vibrational optical coherence tomography (VOCT). VOCT is a new diagnostic technology that uses infrared light and audible sound applied transversely to tissue to measure the resonant frequencies and elastic moduli of cells, dermal collagen, blood vessels and fibrous tissue in skin and lesion stroma without physically touching the skin. Our results indicate that the cellular, vascular and fibrotic resonant frequency peaks are altered in AK, BCC and SCC compared to those peaks observed in normal skin and can serve as physical biomarkers defining the differences between benign and cancerous skin lesions. The resonant frequency is increased from a value of 50 Hz in normal skin to a value of about 80 Hz in pre- and cancerous lesions. A new vascular peak is seen at 130 Hz in cancerous lesions that may reflect the formation of new tumor blood vessels. The peak at 260 Hz is similar to that seen in the skin of a subject with Scleroderma and skin wounds that have healed. The peak at 260 Hz appears to be associated with the deposition of large amounts of stiff fibrous collagen in the stroma surrounding cancerous lesions. Based on the results of this pilot study, VOCT can be used to non-invasively identify physical biomarkers that can help differentiate between benign and cancerous skin lesions. The appearance of new stiff cellular, fragile new vessels, and stiff fibrous material based on resonant frequency peaks and changes in the extracellular matrix can be used as a fingerprint of pre- and cancerous skin lesions.

Characterization of Mueller matrix elements for classifying human skin cancer utilizing random forest algorithm

SIGNIFICANCE

The Mueller matrix decomposition method is widely used for the analysis of biological samples. However, its presumed sequential appearance of the basic optical effects (e.g., dichroism, retardance, and depolarization) limits its accuracy and application.

AIM

An approach is proposed for detecting and classifying human melanoma and non-melanoma skin cancer lesions based on the characteristics of the Mueller matrix elements and a random forest (RF) algorithm.

APPROACH

In the proposal technique, 669 data points corresponding to the 16 elements of the Mueller matrices obtained from 32 tissue samples with squamous cell carcinoma (SCC), basal cell carcinoma (BCC), melanoma, and normal features are input into an RF classifier as predictors.

RESULTS

The results show that the proposed model yields an average precision of 93%. Furthermore, the classification results show that for biological tissues, the circular polarization properties (i.e., elements m44, m34, m24, and m14 of the Mueller matrix) dominate the linear polarization properties (i.e., elements m13, m31, m22, and m41 of the Mueller matrix) in determining the classification outcome of the trained classifier.

CONCLUSIONS

Overall, our study provides a simple, accurate, and cost-effective solution for developing a technique for classification and diagnosis of human skin cancer.

Microwave Imaging of Breast Skin Utilizing Elliptical UWB Antenna and Reverse Problems Algorithm

Skin cancer is one of the most widespread and fast growing of all kinds of cancer since it affects the human body easily due to exposure to the Sun's rays. Microwave imaging has shown better outcomes with higher resolution, faster processing time, mobility, and less cutter and artifact effects. A miniaturized elliptical ultra-wideband (UWB) antenna and its semi-spherical array arrangement were used for signal transmission and reception from the defected locations in the breast skin. Several conditions such as various arrays of three, six, and nine antenna elements, smaller tumor, multi-tumors, and skin on a larger breast sample of 30 cm were considered. To assess the ability of the system, a breast shape container with a diameter of 130 mm and height of 60 mm was 3D printed and then filled with fabricated skin and breast fat to perform the experimental investigation. An improved modified time-reversal algorithm (IMTR) was used to recreate 2D images of tumors with the smallest radius of 1.75 mm in any location within the breast skin. The reconstructed images using both simulated and experimental data verified that the system can be a reliable imaging system for skin cancer diagnosis having a high structural similarity index and resolution.

Clinical Diagnosis has a High Negative Predictive Value in Evaluation of Malignant Skin Lesions

Background

The increasing incidence of skin cancers in fair-skinned population and its relatively good response to treatment make its accurate diagnosis of great importance. We evaluated the accuracy of clinical diagnosis of malignant skin lesions by comparing the clinical diagnosis with histological diagnosis as the gold standard.

Materials and Methods

In this retrospective study, we assessed all the pathology reports from specimens sent to a university hospital laboratory in 3 consecutive years from March 2008 to March 2010. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios were calculated for clinical diagnosis of malignant skin lesions stratified by their histological subtype.

Results

A total 4,123 specimen were evaluated. The sensitivity and specificity for clinical diagnosis of malignancy were 90.48% and 82.85%, respectively, whereas the negative predictive value was shown to be 99.06%. The positive and negative likelihood ratios were 5.23 and 0.11, respectively.

Conclusion

Pathological assessment of skin lesions remains the cornerstone of skin cancer diagnosis. The high NPV and the relatively low PPV indicate that clinical diagnosis is more efficient in ruling out malignancies rather than diagnosing them.

Evaluation of ultrahigh-resolution optical coherence tomography for basal cell carcinoma, seborrheic keratosis, and nevus

BACKGROUND

Basal cell carcinoma, seborrheic keratosis, and nevus are common skin conditions. Though most of the skin diseases can be distinguished from each other by physician's naked eyes, the diagnostic accuracy is not 100%. The accurate diagnosis and assessment of three diseases make a big difference on the clinical management. Nowadays, biopsy is still the gold standard for diagnosis even it is invasive, time-consuming, and painful. Ultrahigh-resolution optical coherence tomography is an emerging technology that can produce in situ, cellular-resolution, real-time, continuous, 3D images in a noninvasive way.

MATERIALS AND METHODS

In our study, four basal cell carcinoma patients, five seborrheic keratosis patients, and 10 nevus patients who were diagnosed by histology were studied by ultrahigh-resolution optical coherence tomography after visual examination by experienced dermatologists. Cellular contrast was utilized to clearly identify the features of the three skin diseases.

RESULTS

The features including such as hyperkeratosis (horn pseudocysts), papillomatosis, intraepidermal nests, elongated, and expanded rete ridge can be visualized in seborrheic keratosis. Tumor nodular, mucin surrounding with tumor (retraction space in histopathology), tumor subtype, and necrosis were featured in basal cell carcinoma. Pigment was characterized in epidermis and dermis. The comparison of ultrahigh-resolution optical coherence tomography images reveals a strong correlation with histological images.

CONCLUSION

Ultrahigh-resolution optical coherence tomography can complement existing diagnostic techniques for investigating seborrheic keratosis, basal cell carcinoma and nevus, and show enormous potential in vivo applications for the three skin diseases in the future.

Efficacy and Safety of Laser-Assisted Combination Chemotherapy: An Explorative Imaging-Guided Treatment With 5-Fluorouracil and Cisplatin for Basal Cell Carcinoma

BACKGROUND AND OBJECTIVES

Rising incidences of basal cell carcinoma (BCC) have increased the need for effective topical therapies. By enhancing cutaneous uptake of the chemotherapeutic agents, cisplatin and 5-fluorouracil (5-FU), laser-assisted delivery may provide a new combination treatment for BCC. Accordingly, this study aimed to evaluate tumor response, safety, and drug biodistribution in tumors and blood after topical laser-assisted 5-FU + CIS treatment in BCC patients.

STUDY DESIGN/MATERIALS AND METHODS

This open-label, proof-of-concept trial investigated laser-assisted combination cisplatin + 5-FU treatment in 20 patients with histologically verified, low-risk superficial or nodular BCCs on the face (<20 mm) or trunk/extremities (<50 mm). After tumor demarcation guided by optical coherence tomography (OCT), BCCs were exposed to ablative fractional CO₂ laser followed by 60 minutes topical cisplatin solution and 7-day exposure to 5% 5-FU cream under occlusion. After 30 days, treatment was repeated if any tumor residual was identified. Tumor response at day 30 and month 3 was assessed clinically as well as by OCT, reflectance confocal microscopy, and ultrasound, supplemented by histological verification at 3 months. Local skin reactions (LSRs) and side effects were evaluated on days 1, 3-5, 14, 30, and month 3. Drug detection in tumors and blood was performed in a subset of patients 1- and 24 hours after treatment.

RESULTS

Nineteen patients completed the trial, with 32% (6/19) receiving a single treatment and 68% (13/19) treated twice. At 3 months, clinical clearance was seen in 18/19 patients with a corresponding 94% (17/18) achieving histological clearance. Baseline tumor thickness and subtype did not influence treatment number or clearance rate (P ≥ 0.61). LSRs were well-tolerated and consisted of erythema, edema, and erosion, followed by crusting by day 14. Erythema declined gradually by month 3, with 94% of patients and 79% of physicians rating cosmesis as "good" or "excellent." Scarring or hyperpigmentation was noted in 50% and 56%, respectively, while pain and infection were not observed during the follow-up period. Although chemotherapy uptake was visualized extending to deep skin layers, no systemic exposure to cisplatin or 5-FU was detected in patient blood.

CONCLUSION

Laser-assisted cisplatin + 5-FU shows potential as an effective and tolerable treatment option for low-risk BCC, particularly in instances where self-application is not possible or where in-office, non-surgical therapy is preferred. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Imaging findings of Bowen's disease: A comparison between ultrasound biomicroscopy and conventional high-frequency ultrasound

OBJECTIVES

To compare the imaging findings of Bowen's disease (BD) between ultrasound biomicroscopy (UBM) and conventional high-frequency ultrasound (HFUS).

METHODS

A total of 29 pathologically proven BD lesions in 28 patients were retrospectively enrolled in the study, and all were after surgery. All the lesions were imaged with both UBM and HFUS. The imaging features on HFUS and UBM were analyzed and compared. The diagnostic results of ultrasound for BD were referenced with pathology results.

RESULTS

All the 29 (100%) BD lesions appeared hypoechogenicity, solid component, and superficial hyperechoic layer (ie, keratinization) on both UBM and HFUS. The typical imaging feature of BD lesions, that was, infiltration depth confined to the epidermis, was visualized in 25 (86.2%, 25/29) lesions on UBM whereas 15 (51.7%, 15/29) on HFUS (P = .002). A "wave sign," which corresponds to the surface keratinization of BD lesion, was visualized in 17 (58.6%, 17/29) of BD lesions on UBM whereas 6 (20.7%, 6/29) on HFUS (P = .001). UBM and HFUS correctly diagnosed 25 (86.2%, 25/29) and 15 (51.7%, 15/29) BD lesions, respectively (P = .002).

CONCLUSIONS

Bowen's disease has some typical imaging features on US. The "wave sign" of the superficial hyperechoic layer and the clear borderline between the tumor in epidermis and the slightly hyperechoic dermis layer are better depicted by UBM in comparison with HFUS, which leads to a more accurate diagnosis of BD. UBM has potential to be used as a diagnostic tool for characterization of BD on account of its high resolution.

Multispectral autofluorescence dermoscope for skin lesion assessment

Basal cell carcinoma (BCC) is the most common type of skin cancer. Diagnosis and edge assessment of BCC lesions are based on clinical and dermoscopy evaluation, which are strongly dependent on the expertise and training of the physician. There is a high rate of underdiagnosis because BCC is frequently confused with certain common benign lesions and is often indistinguishable from the surrounding healthy tissue. In the present study, a multispectral fluorescence lifetime imaging (FLIm) dermoscopy system, designed for imaging and analyzing the autofluorescence emission of skin tissue, was used to image thirty-eight patients with diagnosed nodular BCC (nBCC) lesions, using clinically acceptable levels of excitation light exposure. With this system, skin autofluorescence was imaged simultaneously using three emission bands: 390 ± 20 nm, 452 ± 22 nm, and >496 nm, preferentially targeting collagen, NADH, and FAD autofluorescence, respectively. Statistical classifiers based on FLIm features developed to discriminate BCC from healthy tissue showed promising performance (ROC area-under-the-curve of 0.82). This study demonstrates the feasibility of clinically performing multispectral endogenous FLIm dermoscopy providing baseline results indicating the potential of this technology as an image-guided tool to improve the delineation of nBCC during surgical lesion resection.

Recognising Skin Cancer in Primary Care

Skin cancer, including melanoma, basal cell carcinoma and cutaneous squamous cell carcinoma, has one of the highest global incidences of any form of cancer. In 2016 more than 16,000 people were diagnosed with melanoma in the UK. Over the last decade the incidence of melanoma has increased by 50% in the UK, and about one in ten melanomas are diagnosed at a late stage. Among the keratinocyte carcinomas (previously known as non-melanoma skin cancers), basal cell carcinoma is the most common cancer amongst Caucasian populations. The main risk factor for all skin cancer is exposure to ultraviolet radiation-more than 80% are considered preventable. Primary care clinicians have a vital role to play in detecting and managing patients with skin lesions suspected to be skin cancer, as timely diagnosis and treatment can improve patient outcomes, particularly for melanoma. However, detecting skin cancer can be challenging, as common non-malignant skin lesions such as seborrhoeic keratoses share features with less common skin cancers. Given that more than 80% of skin cancers are attributed to ultraviolet (UV) exposure, primary care clinicians can also play an important role in skin cancer prevention. This article is one of a series discussing cancer prevention and detection in primary care. Here we focus on the most common types of skin cancer: melanoma, squamous cell carcinoma and basal cell carcinoma. We describe the main risk factors and prevention advice. We summarise key guidance on the symptoms and signs of skin cancers and their management, including their initial assessment and referral. In addition, we review emerging technologies and diagnostic aids which may become available for use in primary care in the near future, to aid the triage of suspicious skin lesions.

Optical coherence angiography for pre-treatment assessment and treatment monitoring following photodynamic therapy: a basal cell carcinoma patient study

Microvascular networks of human basal cell carcinomas (BCC) and surrounding skin were assessed with optical coherence angiography (OCA) in conjunction with photodynamic therapy (PDT). OCA images were collected and analyzed in 31 lesions pre-treatment, and immediately/24 hours/3-12 months post-treatment. Pre-treatment OCA enabled differentiation between prevalent subtypes of BCC (nodular and superficial) and nodular-with-necrotic-core BCC subtypes with a diagnostic accuracy of 78%; this can facilitate more accurate biopsy reducing sampling error and better therapy regimen selection. Post-treatment OCA images at 24 hours were 98% predictive of eventual outcome. Additional findings highlight the importance of pre-treatment necrotic core, vascular metrics associated with hypertrophic scar formation, and early microvascular changes necessary in both tumorous and peri-tumorous regions to ensure treatment success.

Physiological model using diffuse reflectance spectroscopy for nonmelanoma skin cancer diagnosis

Diffuse reflectance spectroscopy (DRS) is a noninvasive, fast, and low-cost technology with potential to assist cancer diagnosis. The goal of this study was to test the capability of our physiological model, a computational Monte Carlo lookup table inverse model, for nonmelanoma skin cancer diagnosis. We applied this model on a clinical DRS dataset to extract scattering parameters, blood volume fraction, oxygen saturation and vessel radius. We found that the model was able to capture physiological information relevant to skin cancer. We used the extracted parameters to classify (basal cell carcinoma [BCC], squamous cell carcinoma [SCC]) vs actinic keratosis (AK) and (BCC, SCC, AK) vs normal. The area under the receiver operating characteristic curve achieved by the classifiers trained on the parameters extracted using the physiological model is comparable to that of classifiers trained on features extracted via Principal Component Analysis. Our findings suggest that DRS can reveal physiologic characteristics of skin and this physiologic model offers greater flexibility for diagnosing skin cancer than a pure statistical analysis. Physiological parameters extracted from diffuse reflectance spectra data for nonmelanoma skin cancer diagnosis.

Vibration analysis of healthy skin: toward a noninvasive skin diagnosis methodology

Several noninvasive imaging techniques have been developed to monitor the health of skin and enhance the diagnosis of skin diseases. Among them, skin elastography is a popular technique used to measure the elasticity of the skin. A change in the elasticity of the skin can influence its natural frequencies and mode shapes. We propose a technique to use the resonant frequencies and mode shapes of the skin to monitor its health. Our study demonstrates how the resonant frequencies and mode shapes of skin can be obtained using numerical and experimental analysis. In our study, natural frequencies and mode shapes are obtained via two methods: (1) finite element analysis: an eigensolution is performed on a finite element model of normal skin, including stratum corneum, epidermis, dermis, and subcutaneous layers and (2) digital image correlation (DIC): several in-vivo measurements have been performed using DIC. The experimental results show a correlation between the DIC and FE results suggesting a noninvasive method to obtain vibration properties of the skin. This method can be further examined to be eventually used as a method to differentiate healthy skin from diseased skin. Prevention, early diagnosis, and treatment are critical in helping to reduce the incidence, morbidity, and mortality associated with skin cancer; thus, making the current study significant and important in the field of skin biomechanics.

Reflectance confocal microscopy for diagnosing keratinocyte skin cancers in adults

BACKGROUND

Early accurate detection of all skin cancer types is important to guide appropriate management and improve morbidity and survival. Basal cell carcinoma (BCC) is usually a localised skin cancer but with potential to infiltrate and damage surrounding tissue, whereas cutaneous squamous cell carcinoma (cSCC) and melanoma are higher risk skin cancers with the potential to metastasise and ultimately lead to death. When used in conjunction with clinical or dermoscopic suspicion of malignancy, or both, reflectance confocal microscopy (RCM) may help to identify cancers eligible for non-surgical treatment without the need for a diagnostic biopsy, particularly in people with suspected BCC. Any potential benefit must be balanced against the risk of any misdiagnoses.

OBJECTIVES

To determine the diagnostic accuracy of RCM for the detection of BCC, cSCC, or any skin cancer in adults with any suspicious lesion and lesions that are difficult to diagnose (equivocal); and to compare its accuracy with that of usual practice (visual inspection or dermoscopy, or both).

SEARCH METHODS

We undertook a comprehensive search of the following databases from inception to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists and published systematic review articles.

SELECTION CRITERIA

Studies of any design that evaluated the accuracy of RCM alone, or RCM in comparison to visual inspection or dermoscopy, or both, in adults with lesions suspicious for skin cancer compared with a reference standard of either histological confirmation or clinical follow-up, or both.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data using a standardised data extraction and quality assessment form (based on QUADAS-2). We contacted authors of included studies where information related to the target condition or diagnostic threshold were missing. We estimated summary sensitivities and specificities using the bivariate hierarchical model. For computation of likely numbers of true-positive, false-positive, false-negative, and true-negative findings in the 'Summary of findings' tables, we applied summary sensitivity and specificity estimates to lower quartile, median and upper quartiles of the prevalence observed in the study groups. We also investigated the impact of observer experience.

MAIN RESULTS

The review included 10 studies reporting on 11 study cohorts. All 11 cohorts reported data for the detection of BCC, including 2037 lesions (464 with BCC); and four cohorts reported data for the detection of cSCC, including 834 lesions (71 with cSCC). Only one study also reported data for the detection of BCC or cSCC using dermoscopy, limiting comparisons between RCM and dermoscopy. Studies were at high or unclear risk of bias across almost all methodological quality domains, and were of high or unclear concern regarding applicability of the evidence. Selective participant recruitment, unclear blinding of the reference test, and exclusions due to image quality or technical difficulties were observed. It was unclear whether studies were representative of populations eligible for testing with RCM, and test interpretation was often undertaken using images, remotely from the participant and the interpreter blinded to clinical information that would normally be available in practice.Meta-analysis found RCM to be more sensitive but less specific for the detection of BCC in studies of participants with equivocal lesions (sensitivity 94%, 95% confidence interval (CI) 79% to 98%; specificity 85%, 95% CI 72% to 92%; 3 studies) compared to studies that included any suspicious lesion (sensitivity 76%, 95% CI 45% to 92%; specificity 95%, 95% CI 66% to 99%; 4 studies), although CIs were wide. At the median prevalence of disease of 12.5% observed in studies including any suspicious lesion, applying these results to a hypothetical population of 1000 lesions results in 30 BCCs missed with 44 false-positive results (lesions misdiagnosed as BCCs). At the median prevalence of disease of 15% observed in studies of equivocal lesions, nine BCCs would be missed with 128 false-positive results in a population of 1000 lesions. Across both sets of studies, up to 15% of these false-positive lesions were observed to be melanomas mistaken for BCCs. There was some suggestion of higher sensitivities in studies with more experienced observers. Summary sensitivity and specificity could not be estimated for the detection of cSCC due to paucity of data.

AUTHORS' CONCLUSIONS

There is insufficient evidence for the use of RCM for the diagnosis of BCC or cSCC in either population group. A possible role for RCM in clinical practice is as a tool to avoid diagnostic biopsies in lesions with a relatively high clinical suspicion of BCC. The potential for, and consequences of, misclassification of other skin cancers such as melanoma as BCCs requires further research. Importantly, data are lacking that compare RCM to standard clinical practice (with or without dermoscopy).

Application of cmOCT and continuous wavelet transform analysis to the assessment of skin microcirculation dynamics

Correlation mapping optical coherence tomography (cmOCT) is a powerful technique for the imaging of skin microvessels structure, based on the discrimination of the static and dynamic regions of the tissue. Although the suitability of cmOCT to visualize the microcirculation has been proved in humans and animal models, less evidence has been provided about its application to examine functional dynamics. Therefore, the goal of this research was validating the cmOCT method for the investigation into microvascular function and vasomotion. A spectral domain optical coherence tomography (SD-OCT) device was employed to image 90 sequential three-dimensional (3-D) OCT volumes from the forearm of 12 volunteers during a 25-min postocclusive reactive hyperemia (PORH) test. The volumes were processed using cmOCT to generate blood flow maps at selected cutaneous depths. The maps clearly trace flow variations during the PORH response for both capillaries and arterioles/venules microvascular layers. Continuous blood flow signals were reconstructed from cmOCT maps to study vasomotion by applying wavelet transform spectral analysis, which revealed fluctuations of flow during PORH, reflecting the regulation of microvascular tone mediated by endothelial cells and sympathetic nerves. The results clearly demonstrate that cmOCT allows the generation of functional information that may be used for diagnostic applications.

Noninvasive optical spectroscopy for identification of non-melanoma skin cancer: Pilot study

OBJECTIVE

Optical spectroscopy offers a noninvasive alternative to biopsy as a first-line screening tool for suspicious skin lesions. This study sought to define several optical parameters across malignant and benign tissue types.

STUDY DESIGN

Prospective pilot trial utilizing the Zenalux IM1 optical spectroscopy device from April 2016 to February 2017. For each skin lesion, provider pre-biopsy probability of malignancy was compared to histolopathologic diagnosis. Optical data were characterized across basal cell carcinoma (BCC; n = 9), squamous cell carcinoma (SCC; n = 5), actinic keratosis (AK; n = 4), scar tissue (n = 6), nevus (n = 2), and neurofibroma (NF; n = 1). Across all patients, agreement was determined between control measurements collected adjacent to the lesion and from the upper extremity.

METHODS

Prospective single center pilot study. The optical properties of 27 cutaneous lesions were collected from 18 adult patients presenting to Otolaryngology and Dermatology clinics with suspicious skin lesions warranting biopsy. Spectroscopy measurements were recorded for each lesion: two at the lesion site, two at an adjacent site (internal control), and one at the central medial upper extremity (arm control). Variables of interest included absolute oxygenated hemoglobin (Hb), Hb saturation, total Hb concentration, and Eumelanin concentration. For each lesion, internal control averages were subtracted from lesion averages to provide delta parameter values, and lesion averages were divided by internal control averages to provide ratio parameter values.

RESULTS

Mean percent difference between pre-biopsy probability of malignancy and histology was 29%, with a difference of 75% or greater seen in 5 of 25 lesions. Mean values for BCC, SCC, AK, and scar tissue varied most between extracted mean reduced scatter estimate (μa'; cm- ) delta values (BCC: -2.2 ± 3.8; SCC: -3.9 ± 2.0; AK: -3.3 ± 4.2, Scar: -1.7 ± 1.2) and total Hb (µM) ratio (BCC: 2.0 ± 3.3; SCC: 3.0 ± 1.3; AK: 1.1 ± 0.6; Scar: 1.4 ± 1.1). Agreement between local and arm controls was poor.

CONCLUSION

This pilot trial utilizes optical spectroscopy as a noninvasive method for determining cutaneous lesion histology. Effect sizes observed across optical parameters for benign and malignant tissue types will guide larger prospective studies that may ultimately lead to prediction of lesional histology without need for invasive biopsy. Lasers Surg. Med. 50:246-252, 2018. © 2018 Wiley Periodicals, Inc.

Optical coherence tomography for the diagnosis of malignant skin tumors: a meta-analysis

Optical coherence tomography (OCT) is an emergent imaging tool used for noninvasive diagnosis of skin diseases. The present meta-analysis was carried out to assess the accuracy of OCT for the diagnosis of skin cancer. We conducted a systematic literature search though EMBASE, Medline, PubMed, the Cochrane Library, and Web of Science database for relevant articles published up to June 6, 2017. The quality of the included studies was assessed using the QUADAS-2 tool and the Oxford Levels of Evidence Scale. Statistical analyses were conducted using the software Meta-Disc version 1.4 and STATA version 12.0. A total of 14 studies involving more than 813 patients with a total of 1958 lesions were included in our analyses. The pooled sensitivity and specificity of OCT for skin cancer diagnoses were 91.8% and 86.7%, respectively. Subgroup analysis showed that the pooled sensitivities of OCT for detecting basal cell carcinoma (BCC), squamous cell carcinoma (SCC), actinic keratosis, and malignant melanoma were 92.4%, 92.3%, 73.8%, and 81.0%, respectively. The pooled specificities were 86.9%, 99.5%, 91.5%, and 93.8%, respectively. OCT appears to be useful for the detection of BCC and SCC. It is a valuable diagnostic method when screening for early skin cancers.

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.

Multimodal fluorescence molecular imaging for in vivo characterization of skin cancer using endogenous and exogenous fluorophores

Similarity of skin cancer with many benign skin pathologies requires reliable methods to detect and differentiate the different types of these lesions. Previous studies have explored the use of disparate optical techniques to identify and estimate the invasive nature of melanoma and basal cell carcinoma with varying outcomes. Here, we used a concerted approach that provides complementary information for rapid screening and characterization of tumors, focusing on squamous cell carcinoma (SCC) of the skin. Assessment of in vivo autofluorescence lifetime (FLT) imaging of endogenous fluorophores that are excitable at longer wavelengths (480 nm) than conventional NADH and FAD revealed a decrease in the short FLT component for SCC compared to normal skin, with mean values of 0.57 ± 0.026 ?? ns and 0.61 ± 0.021 ?? ns , respectively ( p = 0.004 ). Subsequent systemic administration of a near-infrared fluorescent molecular probe in SCC bearing mice, followed by the implementation of image processing methods on data acquired from two-dimensional and three-dimensional fluorescence molecular imaging, allowed us to estimate the tumor volume and depth, as well as quantify the fluorescent probe in the tumor. The result suggests the involvement of lipofuscin-like lipopigments and riboflavin in SCC metabolism and serves as a model for staging SCC.

Imaging Blood Vessel Morphology in Skin: Dynamic Optical Coherence Tomography as a Novel Potential Diagnostic Tool in Dermatology

Conventional optical coherence tomography (OCT) enables the visualization of morphological changes of skin cancer. The use of OCT in the diagnostic investigation and in the therapy decision of non-melanoma skin cancer and other skin changes is already established, and has found its way into routine practice. With the development of speckle-variance OCT, also named dynamic OCT (D-OCT), the vascular architecture and the blood flow of the skin can be displayed in vivo and in 3D. This novel angiographic variant of OCT offers the ability to visualize and measure vessel morphology providing a new insight into healthy, inflammatory and neoplastic skin lesions such as malignant melanoma. This review focuses on the possibilities of using D-OCT on healthy and diseased skin. We suggest and illustrate key diagnostic characteristics by analyzing the initial publications and preliminary unpublished data on vessel morphology and distribution. The potential of D-OCT as a diagnostic tool in dermatology is examined and may give rise to future studies on D-OCT, which are needed to confirm the aforementioned features.

An Infrared Absorbance Sensor for the Detection of Melanoma in Skin Biopsies

An infrared (IR) absorbance sensor has been designed, realized and tested with the aim of detecting malignant melanomas in human skin biopsies. The sensor has been designed to obtain fast measurements (80 s) of a biopsy using a small light spot (0.5 mm in diameter, typically five to 10 times smaller than the biopsy size) to investigate different biopsy areas. The sensor has been equipped with a monochromator to record the whole IR spectrum in the 3330-3570 nm wavelength range (where methylene and methyl stretching vibrations occur) for a qualitative spectral investigation. From the collected spectra, the CH₂ stretch ratio values (ratio of the absorption intensities of the symmetric to asymmetric CH₂ stretching peaks) are determined and studied as a cancer indicator. Melanoma areas exhibit different spectral shapes and significantly higher CH₂ stretch ratios when compared to healthy skin. The results of the infrared investigation are compared with standard histology. This study shows that the IR sensor is a promising supportive tool to improve the diagnosis of melanoma during histopathological analysis, decreasing the risk of misdiagnosis.

High correlation of double Debye model parameters in skin cancer detection

The double Debye model can be used to capture the dielectric response of human skin in terahertz regime due to high water content in the tissue. The increased water proportion is widely considered as a biomarker of carcinogenesis, which gives rise of using this model in skin cancer detection. Therefore, the goal of this paper is to provide a specific analysis of the double Debye parameters in terms of non-melanoma skin cancer classification. Pearson correlation is applied to investigate the sensitivity of these parameters and their combinations to the variation in tumor percentage of skin samples. The most sensitive parameters are then assessed by using the receiver operating characteristic (ROC) plot to confirm their potential of classifying tumor from normal skin. Our positive outcomes support further steps to clinical application of terahertz imaging in skin cancer delineation.

The sensitivity and specificity of optical coherence tomography for the assisted diagnosis of nonpigmented basal cell carcinoma: an observational study

BACKGROUND

The diagnostic criteria for basal cell carcinoma (BCC) using optical coherence tomography (OCT) have been described previously, but the clinical value of these findings remains unknown.

OBJECTIVES

To investigate the diagnostic value of OCT for BCC in a typical clinical setting. The primary efficacy end point was a diagnosis of BCC for each lesion. Secondary end points were the diagnosis of other possible conditions.

METHODS

This was an observational, prospective, multicentre study in which consecutive patients with nonpigmented pink lesions suspicious for BCC underwent clinical assessment, dermoscopy and OCT, with the diagnosis recorded at each stage. Once all diagnoses had been recorded, the histological results were disclosed. In total 164 patients with 256 lesions were recruited. Histology was missing for 21 lesions, leaving 235 lesions in 155 patients for analysis.

RESULTS

Sixty per cent of lesions (141 of 235) were identified as BCC by histology. A slight increase of sensitivity was noted following OCT, which did not reach statistical significance. The specificity increased significantly from 28·6% by clinical assessment to 54·3% using dermoscopy and to 75·3% with the addition of OCT (P < 0·001). The positive predictive value for the diagnosis of BCC using OCT was 85·2% [95% confidence interval (CI) 78·6-90·4], and the negative predictive value was 92·1% (95% CI 83·6-97·0). The accuracy of diagnosis for all lesions increased from 65·8% with clinical evaluation to 76·2% following additional dermoscopy and to 87·4% with the addition of OCT.

CONCLUSIONS

OCT significantly improved the diagnostic specificity for BCC compared with clinical assessment and dermoscopy alone.

Advances in the in Vivo Raman Spectroscopy of Malignant Skin Tumors Using Portable Instrumentation

Raman spectroscopy has emerged as a promising tool for real-time clinical diagnosis of malignant skin tumors offering a number of potential advantages: it is non-intrusive, it requires no sample preparation, and it features high chemical specificity with minimal water interference. However, in vivo tissue evaluation and accurate histopathological classification remain a challenging task for the successful transition from laboratory prototypes to clinical devices. In the literature, there are numerous reports on the applications of Raman spectroscopy to biomedical research and cancer diagnostics. Nevertheless, cases where real-time, portable instrumentations have been employed for the in vivo evaluation of skin lesions are scarce, despite their advantages in use as medical devices in the clinical setting. This paper reviews the advances in real-time Raman spectroscopy for the in vivo characterization of common skin lesions. The translational momentum of Raman spectroscopy towards the clinical practice is revealed by (i) assembling the technical specifications of portable systems and (ii) analyzing the spectral characteristics of in vivo measurements.

Dermoscopy: not just for dermatologists

Use of dermoscopy has been proven to increase diagnostic accuracy for melanoma. It is frequently used by dermatologists and other healthcare providers during skin cancer screening and in the evaluation of concerning skin lesions. Studies have shown that it is useful in the diagnosis of many nononcologic cutaneous diseases as well as in the monitoring of disease progression and treatment response. Furthermore, dermoscopy has the potential to aid in pathology specimen sectioning, translational research and medical technology development. Its broad applications and ease of use will make it an increasingly influential tool in healthcare. In this article, we review the established uses of dermoscopy by different healthcare providers and its potential future applications.

Dermoscopic characteristics of nodular squamous cell carcinoma and keratoacanthoma

Background:

Nodular squamous cell carcinoma (SCC) and keratoacanthoma (KA) may mimic a variety of other benign and malignant non-pigmented nodules.

Objectives:

To analyze the dermoscopic characteristics of nodular SCC and KA.

Patients/Methods:

Retrospective analysis of 50 nodular SCCs and 8 KAs collected from a tertiary dermatology referral center and a private dermatology practice in Melbourne, Australia, between 1 September 2009 and 1 October 2012. All lesions were nodules; defined as firm, elevated, round, palpable tumors with a diameter of 5 mm or more. Clinical and dermoscopic images were evaluated by two examiners in consensus.

Results:

Signs of keratinization were frequently observed and included keratin crust/scale (90% of SCCs, 100% of KAs), central keratin mass (32% of SCCs, 88% of KAs), white structureless areas (66% of SCCs, 50% of KAs), white circles (32% of SCCs, 38% of KAs) and white keratin pearls (14% of SCCs, 12% of KAs). Hemorrhage was present in 72% of SCCs and 88% of KAs and preferentially occurred centrally and in areas of keratinization. For nodular SCCs and KAs, we observed glomerular vessels (42% and 25% respectively), linear irregular vessels (36% and 25% respectively), atypical vessels (30% and 38% respectively) and hairpin vessels (30% and 25% respectively).

Conclusions:

Hemorrhage, keratinization and vascular features (glomerular, hairpin and linear irregular morphologies) are useful in diagnosing both nodular SCC and KA. Further research on the comparative dermoscopic characteristics of a range of amelanotic nodules is important in order to improve diagnosis of these clinically challenging tumors.

Cost-effectiveness of nonmelanoma skin cancer screening in Crohn's disease patients

BACKGROUND

Several studies have demonstrated an increased risk of nonmelanoma skin cancer (NMSC) in patients with inflammatory bowel disease, with the greatest risk in patients with Crohn's disease (CD). We investigated the cost-effectiveness of NMSC screening in patients with CD.

METHODS

A mathematical model was used to compare lifetime costs, life expectancies, and benefits of NMSC screening in a hypothetical cohort of 100,000 patients with CD. Strategies studied include: (1) Treat NMSC cases as they present and follow affected patients annually; (2) Screen patients with CD annually once they turn 50 years old, treat NMSC cases as they present and follow affected patients annually; (3) Screen patients with CD annually once they start receiving thiopurines, treat NMSC cases as they present and follow affected patients annually; (4) Screen patients with CD annually when they turn 50 years old or start receiving thiopurines, treat NMSC cases as they present, and follow affected patients annually; (5) Screen all patients with CD annually. These strategies were then studied on a biennial basis, accounting for 10 competing strategies.

RESULTS

Screening all patients with CD annually proved the most cost-effective strategy with an average lifetime cost of more than $333,000, a quality-adjusted life expectancy of about 26 QALYs (95% confidence interval: 22-29), ICER of $3263/QALY, and led to early detection of about 94% of incident NMSC cases. The next best strategy was screening all CD patients biennially with an average lifetime cost of more than $328,000 with 24.5 QALYs (95% confidence interval: 21-25). Only 47% of new NMSC cases were detected early with this strategy.

CONCLUSION

At a willingness-to-pay threshold of $50,000, screening all patients with CD annually for NMSC proved the most cost-effective strategy.

The value of spectrophotometric intracutaneous analysis in the noninvasive diagnosis of nonmelanoma skin cancers

BACKGROUND

Spectrophotometric intracutaneous analysis (SIAscopy) is a recently introduced, noninvasive, rapid and practical method for monitoring pigmented lesions, which calculates the amount of collagen, melanin and haemoglobin deep in the papillary dermis.

AIM

To evaluate the value of SIAscopy in the diagnosis of nonmelanoma skin cancers (NMSC).

METHODS

In total, 80 lesions of 76 patients were clinically evaluated by the first investigator, and the data recorded. Eight months after the clinical evaluation, all lesions were evaluated again by the same investigator, using images (SIAgraphs) obtained by the SIAscope. All SIAgraphs were also evaluated by a second investigator, and all dermatoscopic images by a third, independently of each other. All diagnoses were compared with histopathological diagnoses.

RESULTS

The clinical diagnosis was calculated to have a sensitivity of 79% and specificity of 84%. The SIAscopic diagnoses of the first and second investigators had a sensitivity of 55% and 93%, and a specificity of 88% and 53%, respectively, while the dermatoscopic diagnoses of the third investigator had a sensitivity of 86% and specificity of 80%. There was no statistical accordance between the first and second investigators according to the accuracy of SIAscopic diagnoses (P < 0.01). The area under the curve for the receiver operator characteristic was 0.82 for clinical diagnosis, 0.73 and 0.80 for the SIAscopic evaluation of the first and the second investigators, respectively, and 0.87 for the dermatoscopic evaluation of the third investigator.

CONCLUSIONS

Our findings show that dermatoscopic findings are more valuable than SIAscopic and clinical findings for the noninvasive diagnosis of NMSC. We consider that SIAscopy makes no substantial contribution towards the differential diagnosis of NMSC.

Detection and Discrimination of Non-Melanoma Skin Cancer by Multimodal Imaging

Non-melanoma skin cancer (NMSC) belongs to the most frequent human neoplasms. Its exposed location facilitates a fast ambulant treatment. However, in the clinical practice far more lesions are removed than necessary, due to the lack of an efficient pre-operational examination procedure: Standard imaging methods often do not provide a sufficient spatial resolution. The demand for an efficient in vivo imaging technique might be met in the near future by non-linear microscopy. As a first step towards this goal, the appearance of NMSC in various microspectroscopic modalities has to be defined and approaches have to be derived to distinguish healthy skin from NMSC using non-linear optical microscopy. Therefore, in this contribution the appearance of ex vivo NMSC in a combination of coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG) and two photon excited fluorescence (TPEF) imaging—referred as multimodal imaging—is described. Analogous to H&E staining, an overview of the distinct appearances and features of basal cell and squamous cell carcinoma in the complementary modalities is derived, and is expected to boost in vivo studies of this promising technological approach.

Diagnosis of tumors during tissue-conserving surgery with integrated autofluorescence and Raman scattering microscopy

Tissue-conserving surgery is used increasingly in cancer treatment. However, one of the main challenges in this type of surgery is the detection of tumor margins. Histopathology based on tissue sectioning and staining has been the gold standard for cancer diagnosis for more than a century. However, its use during tissue-conserving surgery is limited by time-consuming tissue preparation steps (1-2 h) and the diagnostic variability inherent in subjective image interpretation. Here, we demonstrate an integrated optical technique based on tissue autofluorescence imaging (high sensitivity and high speed but low specificity) and Raman scattering (high sensitivity and high specificity but low speed) that can overcome these limitations. Automated segmentation of autofluorescence images was used to select and prioritize the sampling points for Raman spectroscopy, which then was used to establish the diagnosis based on a spectral classification model (100% sensitivity, 92% specificity per spectrum). This automated sampling strategy allowed objective diagnosis of basal cell carcinoma in skin tissue samples excised during Mohs micrographic surgery faster than frozen section histopathology, and one or two orders of magnitude faster than previous techniques based on infrared or Raman microscopy. We also show that this technique can diagnose the presence or absence of tumors in unsectioned tissue layers, thus eliminating the need for tissue sectioning. This study demonstrates the potential of this technique to provide a rapid and objective intraoperative method to spare healthy tissue and reduce unnecessary surgery by determining whether tumor cells have been removed.

Reflectance confocal microscopy allows in vivo real-time noninvasive assessment of the outcome of methyl aminolaevulinate photodynamic therapy of basal cell carcinoma

BACKGROUND

Photodynamic therapy (PDT) with methyl aminolaevulinate (MAL) is an approved noninvasive treatment option for basal cell carcinoma (BCC). In vivo reflectance confocal microscopy (RCM) is a noninvasive imaging technique that has proved useful for in vivo real-time cytomorphological analysis of BCC cells infiltrating the epidermis.

OBJECTIVES

  To investigate the use of in vivo RCM to assess the persistence of BCC cells surviving MAL-PDT.

METHODS

In vivo  RCM images of 20 biopsy-proven BCCs were taken before patients underwent a treatment cycle with MAL-PDT. Follow-up after 3months was performed using clinical examination, RCM and conventional dermoscopy. Treated areas also underwent a targeted 3-mm punch biopsy for standard haematoxylin and eosin histology stain to establish the clinical and instrumental correlation of the treatment outcome.

RESULTS

  Three months after PDT, clinical examination established that two out of 20 BCCs were persistent; dermoscopy found three out of 20 residual BCCs, but RCM showed that one of these lesions was a false positive, and showed persistent BCC foci in five out of 20 lesions. Histological analysis of targeted biopsies confirmed these results.

CONCLUSIONS

  RCM provided noninvasive, early detection of incipient recurrences of BCC after MAL-PDT. RCM findings steered targeted biopsies and surgical removal, or a new MAL-PDT, of these subclinical recurrences with minimal invasiveness.

Imaging of basal cell carcinoma by high-definition optical coherence tomography: histomorphological correlation. A pilot study

BACKGROUND

With the continued development of noninvasive therapies for basal cell carcinoma (BCC) such as photodynamic therapy and immune therapies, noninvasive diagnosis and monitoring become increasingly relevant. High-definition optical coherence tomography (HD-OCT) is a high-resolution imaging tool, with micrometre resolution in both transversal and axial directions, enabling visualization of individual cells up to a depth of around 570 μm, and filling the imaging gap between conventional optical coherence tomography (OCT) and reflectance confocal microscopy (RCM).

OBJECTIVES

We sought to determine the feasibility of detecting BCC by this technique using criteria defined for RCM and conventional OCT and compared with histology.

METHODS

In this pilot study skin lesions of 21 patients with a histologically proven BCC were imaged by HD-OCT just before excision and images analysed qualitatively.

RESULTS

Features for four different BCC subtypes were described in both transverse and axial directions. In general, these features were subepidermal or intradermal aggregations of cells. These islands or trabeculae were surrounded by a less refractile border corresponding with palisading and peritumoral mucin production. There was a pronounced architectural disarray of the epidermis. A variably refractile stroma together with abundant dilated peritumoral blood vessels was present. These features were comparable with histological features for each patient.

CONCLUSIONS

Using features already suggested by RCM and conventional OCT, the study implies that HD-OCT facilitates in vivo diagnosis of BCC and allows the distinction between different BCC subtypes for increased clinical utility.

Multiphoton multispectral fluorescence lifetime tomography for the evaluation of basal cell carcinomas

We present the first detailed study using multispectral multiphoton fluorescence lifetime imaging to differentiate basal cell carcinoma cells (BCCs) from normal keratinocytes. Images were acquired from 19 freshly excised BCCs and 27 samples of normal skin (in & ex vivo). Features from fluorescence lifetime images were used to discriminate BCCs with a sensitivity/specificity of 79%/93% respectively. A mosaic of BCC fluorescence lifetime images covering >1 mm² is also presented, demonstrating the potential for tumour margin delineation.

Using 10,462 manually segmented cells from the image data, we quantify the cellular morphology and spectroscopic differences between BCCs and normal skin for the first time. Statistically significant increases were found in the fluorescence lifetimes of cells from BCCs in all spectral channels, ranging from 19.9% (425–515 nm spectral emission) to 39.8% (620–655 nm emission). A discriminant analysis based diagnostic algorithm allowed the fraction of cells classified as malignant to be calculated for each patient. This yielded a receiver operator characteristic area under the curve for the detection of BCC of 0.83.

We have used both morphological and spectroscopic parameters to discriminate BCC from normal skin, and provide a comprehensive base for how this technique could be used for BCC assessment in clinical practice.

Facial basal cell carcinomas recurring after photodynamic therapy: a retrospective analysis of histological subtypes

BACKGROUND

Photodynamic therapy (PDT) is an established treatment for basal cell carcinomas (BCCs). Although recurrences are sometime observed, their histological patterns have never been specifically studied or compared with the one of the initial tumor.

OBJECTIVE

To compare the histopathological aggressiveness of BCCs recurring after PDT with that of the primary tumors.

METHODS

The study population included 12 patients with 16 post PDT recurrent BCCs. Outcome measures were proportion of histologically aggressive subtypes in BCC recurrences vs. primary tumor.

RESULTS

62.5% of recurrent BCCs displayed a transition from a non-aggressive to an aggressive subtype.

CONCLUSIONS

Post PDT recurrences appear to display an increased histological aggressiveness, although the latter may reflect the natural course of tumor progression. Despite the presence of potential biases, our study raises the possibility that PDT favors the selection of more aggressive tumor cells. Better systematic large-scale follow-up studies are required to assess the exact frequency and histological types of BCC recurrences after PDT.

Advances in dermoscopy for detecting melanocytic lesions

Over the last 30 years dermatological approaches to diagnosis and management of melanocytic lesions have been revolutionized by the introduction of dermoscopy. Continuous improvements are being made in applying the technique, mostly in melanoma diagnosis, follow-up of melanocytic lesions and nevogenesis. Identification of new dermoscopic criteria, such as the dermoscopic island and the blue-black color for thin and nodular melanoma, respectively, further add two new weapons in the dermoscopical armamentarium for diagnosis of otherwise featureless melanoma. Recent advances show that short-term, 3-month, follow-up is the optimum time interval to identify minimal changes in initially featureless melanomas. Nevertheless, long-term follow-up is still useful for the recognition of changes in melanomas with a very low-rate of growth. Dermoscopy greatly improves diagnosis and early excision of melanomas and reduces the number of unnecessary excisions.

In vivo measurements of diffuse reflectance and time-resolved autofluorescence emission spectra of basal cell carcinomas

We present a clinical investigation of diffuse reflectance and time-resolved autofluorescence spectra of skin cancer with an emphasis on basal cell carcinoma. A total of 25 patients were measured using a compact steady-state diffuse reflectance/fluorescence spectrometer and a fibre-optic-coupled multispectral time-resolved spectrofluorometer. Measurements were performed in vivo prior to surgical excision of the investigated region. Singular value decomposition was used to reduce the dimensionality of steady state diffuse reflectance and fluorescence spectra. Linear discriminant analysis was then applied to the measurements of basal cell carcinomas (BCCs) and used to predict the tissue disease state with a leave-one-out methodology. This approach was able to correctly diagnose 87% of the BCCs. With 445 nm excitation a decrease in the spectrally averaged fluorescence lifetime was observed between normal tissue and BCC lesions with a mean value of 886 ps. Furthermore, the fluorescence lifetime for BCCs was lower than that of the surrounding healthy tissue in all cases and statistical analysis of the data revealed that this decrease was significant (p = 0.002).

PpIX fluorescence combined with auto-fluorescence is more accurate than PpIX fluorescence alone in fluorescence detection of non-melanoma skin cancer: an intra-patient direct comparison study

BACKGROUND

Previous research on fluorescence detection of non-melanoma had mixed results. An accurate non-invasive method for the detection of skin cancer is valuable to dermatologists because of the high incidence of skin cancer among the aging population. One notable difference between the methods of fluorescence detection previously studied was the use of the auto-fluorescence of the skin. Currently, there has not been a direct comparison between both methods of fluorescence detection.

OBJECTIVE

To compare the accuracy of PpIX fluorescence and auto-fluorescence normalized PpIX fluorescence detection systems for the localization non-melanoma skin cancers (NMSC).

METHODS

We conducted an observer blinded direct comparison of both methods. Thirty patients, 14 females and16 males, mean age 62 (SD = 9 years), skin type I to III and being suspected of having one or more NMSC, visited an independent treatment centre for dermatology. The patients were investigated using a fluorescence detection system capable of both normalized and non-normalized PpIX fluorescence measurements. Liposomal encapsulated 5-aminolevulinic acid was used as a photosensitizer. For each area being investigated, the associated normalized and non-normalized fluorescence measurements were directly compared. The results of the analysis were confirmed by clinical investigation using a dermatoscope. Both methods were evaluated based on the number of true and false positives and the number of true and false negatives. Specificity and sensitivity were calculated. Statistical significance of the findings was determined using Pearson's Chi-squared test.

RESULTS

The non-normalized method was found to have a sensitivity of 27 % and a specificity of 39 % and the normalized method has a sensitivity of 97% and a specificity of 100%. This difference is statistically significant (p < 0.05).

CONCLUSION

Using auto-fluorescence in PpIX fluorescence detection of NMSC is more accurate that PpIX fluorescence detection alone.