Histopathology and reflectance confocal microscopy features of photodamaged skin and actinic keratosis.

BACKGROUND: Actinic keratosis (AK) usually co-exists in areas of severe photodamage, but the clinical applicability of reflectance confocal microscopy (RCM) in diagnosing AK currently depends on a set of parameters yet to be defined in comparison to photodamaged skin (PD). OBJECTIVE: To correlate the RCM features of PD and AK with histopathology. METHODS: Twenty participants with a mean age of 64 years and skin phototype I and II were studied. RCM was performed on two PD and one AK within a field of 25 cm2 on the left dorsal forearm, followed by shave biopsies. Blinded evaluation of the histopathological and RCM images using established parameters in AK were performed retrospectively in consensus with an expert confocalist, correlated with the histopathological diagnosis by a board-certified dermatopathologist. RESULTS: A total of 57/60 areas were included. There were 43/57 (75%) and 14/57 (25%) histopathologically confirmed PD and AK respectively. Individual corneocytes, stratum corneum disruption, dermal inflammatory cells, increased vascularity/dilated vessels and solar elastosis were detected in PD and AK upon histopathology and RCM. The features in favour of AK were parakeratosis, hyperkeratosis, more severe keratinocyte pleomorphism and architectural disruption, and the presence of epidermal inflammatory cells. PD also demonstrated keratinocyte pleomorphism and architectural disruption though this was generally less severe than AK. A small subset of PD exhibited a comparable degree of keratinocyte pleomorphism and architectural disruption to the AKs in the cohort. CONCLUSIONS: The viable epidermis demonstrates PD and AK to be part of a disease continuum corresponding to field cancerization. Individual corneocytes, stratum corneum disruption, dermal inflammatory cells, increased vascularity/dilated vessels and solar elastosis may be present in PD; whereas, parakeratosis and hyperkeratosis may represent the key to distinguishing AK from PD using RCM. The significance of epidermal inflammatory cells in the RCM diagnosis of AK remains to be elucidated.

A randomized, phase IIa exploratory trial to assess the safety and preliminary efficacy of LEO 43204 in patients with actinic keratosis.

BACKGROUND: LEO 43204 is a novel ingenol derivative in development for the treatment of actinic keratosis. OBJECTIVES: To compare the safety and preliminary efficacy of three doses of LEO 43204 with ingenol mebutate in actinic keratoses (AKs). METHODS: Patients with at least three visible, discrete, nonkeratotic AKs on four separate selected treatment areas on the forearms received LEO 43204 gel (0·025%, 0·05% and 0·075%) and ingenol mebutate 0·05% gel, by investigator-blinded, randomized allocation, for 2 consecutive days. Patients were assessed at 8 weeks. Primary outcomes included maximum composite local skin response (LSR) score and adverse events (AEs). Secondary outcomes included a reduction in the number of visible AKs. RESULTS: Forty patients completed the trial. For all treatments, mean LSR scores peaked at week 1, and were below baseline by week 8. Mean maximum composite LSR scores for LEO 43204 0·025%, 0·05% and 0·075% were 9·2 (Dunnett adjusted P = 0·02), 10·1 (Dunnett adjusted P = 0·90) and 11·2 (Dunnett adjusted P < 0·01), respectively, vs. ingenol mebutate 0·05% gel (10·0). The most frequent AEs across all treatments were application site pruritus, burning sensation and tenderness. Mean reduction in the number of AKs was comparable for ingenol mebutate and the two lowest doses of LEO 43204 (71·9-73·1%), but LEO 43204 0·075% gave a significantly larger reduction (81·8%; Dunnett adjusted P = 0·04). CONCLUSIONS: LEO 43204 had a similar safety profile to ingenol mebutate and a dose-response relationship for LSRs was demonstrated. The highest LEO 43204 dose (0·075%) significantly reduced the AK count when compared with ingenol mebutate.

Reflectance confocal microscopy for inflammatory skin diseases.

Reflectance confocal microscopy evaluation of inflammatory skin diseases represents a relatively new indication that, during the last 5 years, has shown an increasing interest with consequent progressive increment of publications in literature. The success of RCM in this filed of dermatology is directly related to the high needing of non-invasive techniques able to reduce the number of skin biopsies and support the clinical diagnosis and patient's management. RCM demonstrated to visualize microscopic descriptors of inflammatory and pigmentary skin conditions with good reproducibility between observer and high grade of correspondence with optical histology. Moreover, RCM has shown to provide sufficient data to support clinical diagnosis and differential diagnosis of inflammatory and pigmentary skin diseases. Recently, several works published in literature have opened the prospective to use RCM also for therapeutic follow-up in order to monitor the improvement of the microscopic parameters and help to prevent treatment side effects. In this review article we present some examples of RCM application in inflammatory and pigmentary diseases.

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.

In vivo assessment of chronological ageing and photoageing in forearm skin using reflectance confocal microscopy.

BACKGROUND: Skin ageing is a complex process due to intrinsic chronological factors (chronoageing) and extrinsic environmental factors. The primary extrinsic factor is cumulative ultraviolet (UV) exposure, and is therefore termed photoageing. The current standards for measuring cumulative sun damage are biopsy histology and skin microtopography. However, skin biopsies are too invasive for population studies and skin replicas render only superficial skin architecture data. Reflectance confocal microscopy (RCM) is a noninvasive imaging tool that allows for in vivo imaging of the skin at quasihistological resolution. OBJECTIVES: To define and identify RCM features associated with chronological ageing and photoageing on the forearm in two age groups with different skin phototypes and to assess whether these results agree with previous findings. METHODS: We obtained RCM images of dorsal and volar nonlesional skin of the lower forearm of 75 individuals with skin Fitzpatrick phototypes I-III in two age groups (20-30 years and 50-60 years). From each participant and body site, 21 RCM features were assessed and statistically significant differences between the two age groups and different forearm sites determined. RESULTS: RCM enabled identification of changes in architecture, cell morphology and extracellular matrix (collagen) at the level of the epidermis, dermoepidermal junction and papillary dermis. Changes that were correlated with chronological ageing and which were aggravated on the UV-exposed dorsal forearm were: loss of small skin furrows resulting in wider and less intersecting furrows; irregularity of the epidermal honeycomb pattern; irregularly distributed (mottled) pigmented keratinocytes/melanocytes; irregularity of the papillary rings and/or effacement of the rete ridges; and loss of thin collagen fibres and presence of collagen clods. CONCLUSION: We have tested previously reported and new parameters for skin ageing evaluation by RCM, and identified 15 statistically significant RCM features that can be used to quantify ageing and photoageing in forearm skin noninvasively.

Cutaneous short-interfering RNA therapy.

Since the 1990s, RNA interference (RNAi) has become a major subject of interest, not only as a tool for biological research, but also, more importantly, as a therapeutic approach for gene-related diseases. The use of short-interfering RNAs (siRNAs) for the sequence-specific knockdown of disease-causing genes has led to numerous preclinical and even a few clinical studies. Applications for cutaneous delivery of therapeutic siRNA are now emerging owing to a strong demand for effective treatments of various cutaneous disorders. Although successful studies have been performed using several different delivery techniques, most of these techniques encounter limitations for translation to the clinic with regards to patient compliance. This review describes the principal findings and applications in cutaneous RNAi therapy and focuses on the promises and pitfalls of the delivery systems.