Reflectance Confocal Microscopy for Noninvasive Monitoring of Therapy and Detection of Subclinical Actinic Keratoses

Abstract

Background: Actinic keratoses (AK) represent cutaneous carcinoma in situ and have previously been evaluated by reflectance confocal microscopy (RCM). Treatment of AK with imiquimod (IMIQ) 5% cream has been shown to ‘highlight’ subclinical lesions. Objective: The aim of this study was to test the applicability of RCM for noninvasive monitoring of actinic field cancerization and detection of subclinical AK. Subjects and Methods: AK and surrounding skin sites with no apparent AK of 11 volunteers were selected for imaging and subsequently classified as ‘clinical’ and ‘subclinical’ AK. IMIQ was used 3 times weekly for 4 weeks. Results: RCM was able to detect morphologic features of AK in both clinical and subclinical AK; features were more pronounced in clinical lesions. The immunomodulatory response induced by IMIQ was visualized by RCM. Conclusion: Our findings indicate that RCM allows noninvasive monitoring of treatment response in vivo and permits early detection of subclinical AK, thus substantiating the incentive for therapy.

In vivo fluorescence confocal microscopy: indocyanine green enhances the contrast of epidermal and dermal structures

“…Assessment and follow-up of exactly the same skin site can be performed as no tissue is removed. 17 Several such tools based on optical imaging have emerged in the recent past. High-frequency ultrasound, for example, uses ultrasound frequencies between 3 and 100 MHz to evaluate skin morphology and enables a high penetration depth.…”

Confocal Laser Scanning Microscopy as a Tool for the Investigation of Skin Drug Delivery Systems and Diagnosis of Skin Disorders

“…In dermatology, CRM has several uses, such as: i) to diagnose diseases non-invasively in vivo [69][70][71][72]; ii) to non-invasive monitoring of treatment response in vivo and permits early detection of subclinical disease [73]; iii) to improve the accuracy of clinical diagnosis [74]; iv) to improve clinical discrimination between benign and malignant lesions [75]; v) to evaluate the same skin site over time because it produces no tissue damage [76]; vi) to assess the boundaries of the lesion pre-or post-surgery [54]; vii) to evaluate the dynamics of structural and cellular changes that take place during the occurrence of the disease [77]; and viii) to study physiopathologic processes non-invasively over time [78][79].…”

“…Later, others confirmed the usefulness of this tool [73,[88][89], although it has not been able to unequivocally differentiate actinic keratosis from squamous cell carcinomas [90]. Non-melanoma skin cancers (NMSC) were evaluated by fluorescence confocal microscopy aiming to diagnose and monitor the lesions in reference to normal skin and correlation with routine histology.…”

Real-world approach to actinic keratosis management: practical treatment algorithm for office-based dermatology

“…In the future, novel imaging techniques such as reflectance confocal microscopy and optical coherence tomography may be useful in the diagnosis of AK (5,26,27).…”

“…As ultraviolet radiation affects the entire sun-exposed area of skin, clinically visible AK lesions are surrounded by subclinical or invisible lesions resulting in field cancerisation ( Figure 1) (4,5). AK lesions can be considered as early in situ squamous cell carcinoma (SCC) and part of a disease continuum that can progress into invasive SCC (1)(2)(3).…”