The diagnostic value of in vivo reflectance confocal microscopy in actinic keratosis

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.

Reflectance Confocal Microscopy and Dermoscopy for the Diagnosis of Solitary Hypopigmented Pink Lesions: A Narrative Review

Diagnosing solitary pink skin lesions poses a significant challenge due to the scarcity of specific clinical and dermoscopic criteria. Several benign lesions, such as cherry angioma, clear cell acanthoma, dermal nevus, keloid, hypertrophic scar, and Spitz nevus, often exhibit similar clinical and dermoscopic features. This similarity extends to some malignant lesions, including basal cell carcinoma, actinic keratosis, and amelanotic melanoma, making differentiation difficult. Recent studies highlight the enhanced diagnostic accuracy of reflectance confocal microscopy (RCM), which offers increased sensitivity and specificity compared to dermoscopy alone for diagnosing skin cancer. This study aims to summarize the application of dermoscopy and RCM in distinguishing between benign and malignant pinkish-reddish skin lesions. The integration of RCM with traditional dermoscopic techniques improves the ability to accurately identify and differentiate these lesions. However, it is crucial to note that for any suspicious lesions, a final diagnosis must be confirmed through surgical excision and histopathological evaluation. This comprehensive approach ensures accurate diagnosis and appropriate treatment, highlighting the importance of combining advanced imaging techniques in clinical practice.

European consensus-based interdisciplinary guideline for diagnosis, treatment and prevention of actinic keratoses, epithelial UV-induced dysplasia and field cancerization on behalf of European Association of Dermato-Oncology, European Dermatology Forum, European Academy of Dermatology and Venereology and Union of Medical Specialists (Union Européenne des Médecins Spécialistes)

A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology, the European Dermatology Forum, the European Academy of Dermatology and Venereology, and the European Union of Medical Specialists was formed to develop European recommendations on AK diagnosis and treatment, based on current literature and expert consensus. This guideline addresses the epidemiology, diagnostics, risk stratification and treatments in immunocompetent as well as immunosuppressed patients. Actinic keratoses (AK) are potential precursors of cutaneous squamous cell carcinoma (cSCC) and display typical histopathologic and immunohistochemical features of this malignancy in an early stage. They can develop into cSSC in situ and become invasive in a low percentage of cases. AK is the most frequent neoplasia in white populations, frequently occurring within a cancerous field induced by ultraviolet radiation. Since it cannot be predicted, which lesion will progress to cSCC and when treatment is usually recommended. The diagnosis of AK and field cancerization is made by clinical examination. Dermatoscopy, confocal microscopy, optical coherence tomography or line-field confocal-OCT can help in the differential diagnosis of AK and other skin neoplasms. A biopsy is indicated in clinically and/or dermatoscopically suspicious and/or treatment-refractory lesions. The choice of treatment depends on patients' and lesion characteristics. For single non-hyperkeratotic lesions, the treatment can be started upon patient's request with destructive treatments or topical treatments. For multiple lesions, field cancerization treatment is advised with topical treatments and photodynamic therapy. Preventive measures such as sun protection, self-examination and repeated field cancerization treatments of previously affected skin areas in high-risk patients are advised.

Line-field confocal optical coherence tomography of lentigo maligna with horizontal and vertical histopathologic correlations

Lentigo maligna (LM) is a subtype of in situ melanoma that classically presents in elderly patients as a slowly growing lesion on sun-exposed areas that may evolve to invasive melanoma. Line-field confocal optical coherence tomography (LC-OCT) is a new non-invasive technique for a real-time, vertical, and horizontal skin imaging with high resolution close to conventional histopathology. We present the LC-OCT features of an LM of the nose in a 49-year-old white man along with their horizontal and vertical histopathological correlations. LC-OCT was able to detect in vivo, in both horizontal and vertical imaging, the main microscopic features typical of LM by showing, in the epidermis and around the hair follicles, the presence of large, bright roundish, or dendritic atypical cells, with evident nuclei, corresponding to atypical melanocytes with a tendency toward folliculotropism. A strong correspondence between LC-OCT images and vertical and horizontal histopathological sections was observed. Our study, although limited to a single case, is indicative of the great potential of LC-OCT to improve the non-invasive diagnosis of LM.

A Review of Existing Therapies for Actinic Keratosis: Current Status and Future Directions

Actinic keratosis (AK) is a chronic skin disease in which clinical and subclinical cutaneous lesions coexist on sun-exposed areas such as the head and neck region and the extremities. The high prevalence of AK means the disease burden is substantial, especially in middle-aged and elderly populations. Evidence indicates that AK may progress into invasive cutaneous squamous cell carcinoma, so the European guidelines recommend treatment of any AK regardless of clinical severity. Given the aging population and therefore the increasing incidence of AK and cutaneous field carcinogenesis, further updates on the long-term efficacy of current therapies and new investigational agents are critical to guide treatment choice. Patients often have difficulty adequately applying topical treatments and coping with adverse local skin reactions, leading to less than optimum treatment adherence. The development of associated local skin symptoms and cosmetic outcomes for the area of interest are also relevant to the choice of an appropriate therapeutic strategy. Treatment is always individually tailored according to the characteristics of both patients and lesions. This review focuses on the therapeutic approaches to AK and illustrates the currently available home-based and physician-managed treatments.

In vivo reflectance confocal microscopy for monitoring actinic keratosis treated with 5-aminolevulinic acid photodynamic therapy

BACKGROUND

Actinic keratosis (AK) occurs frequently in sun-exposed skin while its diagnosis and treatment were still in exploration.

MATERIALS AND METHODS

Thirty two patients with facial AK lesions were selected and examined with reflective confocal microscopy (RCM) firstly, followed by biopsy at the same site. RCM was used to observe AK lesions before 5-aminolevulinic acid photodynamic therapy (ALA-PDT) treatment, after the first treatment, after 4 treatments, and at 1 and 6 months follow-up. Retrospective analysis of RCM images was performed.

RESULTS

Thirty two AK cases showed initial RCM microscopic features including disorderly arranged epidermal cells (100%), atypical keratinocytes (100%), and blurry border between the epidermis and dermis (100%). 4 patients quitted trail. After treatments, 24 cases showed basically regular arrangement of epidermal cells, absent atypical keratinocytes, and clear border between epidermis and dermis, while 4 cases improved little. At 1 and 6 months follow-up, 23 cases remained relapse-free while 1 case developed recurrent symptoms. Effective rate of 4 ALA-PDT treatments for AK was 100%; recurrence and cure rates were 4.2% and 82.1%, respectively.

CONCLUSION

ALA-PDT is effective to treat AK, while RCM can be recommended for in vivo evaluating and monitoring the effect of ALA-PDT on AK.