Fragility of epidermis in newborns, children and adolescents.

Within their first days of life, newborns' skin undergoes various adaptation processes needed to accommodate the transition from the wet uterine environment to the dry atmosphere. The skin of newborns and infants is considered as a physiological fragile skin, a skin with lower resistance to aggressions. Fragile skin is divided into four categories up to its origin: physiological fragile skin (age, location), pathological fragile skin (acute and chronic), circumstantial fragile skin (due to environmental extrinsic factors or intrinsic factors such as stress) and iatrogenic fragile skin. Extensive research of the past 10 years have proven evidence that at birth albeit showing a nearly perfect appearance, newborn skin is structurally and functionally immature compared to adult skin undergoing a physiological maturation process after birth at least throughout the first year of life. This article is an overview of all known data about fragility of epidermis in 'fragile populations': newborns, children and adolescents. It includes the recent pathological, pathophysiological and clinical data about fragility of epidermis in various dermatological diseases, such as atopic dermatitis, acne, rosacea, contact dermatitis, irritative dermatitis and focus on UV protection.

Fragility of epidermis and its consequence in dermatology.

The skin is the largest organ of the body, providing a protective barrier against bacteria, chemicals and physical insults while maintaining homeostasis in the internal environment. Such a barrier function the skin ensures protection against excessive water loss. The skin's immune defence consists of several facets, including immediate, non-specific mechanisms (innate immunity) and delayed, stimulus-specific responses (adaptive immunity), which contribute to fending off a wide range of potentially invasive microorganisms. This article is an overview of all known data about 'fragile skin'. Fragile skin is defined as skin with lower resistance to aggressions. Fragile skin can be classified into four categories up to its origin: physiological fragile skin (age, location), pathological fragile skin (acute and chronic), circumstantial fragile skin (due to environmental extrinsic factors or intrinsic factors such as stress) and iatrogenic fragile skin. This article includes the epidemiologic data, pathologic description of fragile skin with pathophysiological bases (mechanical and immunological role of skin barrier) and clinical description of fragile skin in atopic dermatitis, in acne, in rosacea, in psoriasis, in contact dermatitis and other dermatologic pathologies. This article includes also clinical cases and differential diagnosis of fragile skin (reactive skin) in face in adult population. In conclusion, fragile skin is very frequent worldwide and its prevalence varies between 25% and 52% in Caucasian, African and Asian population.

A multitechnique evaluation of topical corticosteroid treatment.

BACKGROUND/PURPOSE: Corticosteroids are widely prescribed for systemic or local treatment of inflammatory autoimmune disorders. Long-term therapy is associated with side effects and causes cutaneous atrophy of the epidermis and the dermis. The present study aims to evaluate with several noninvasive techniques, the skin modifications observed during corticosteroids treatment. The potential of skin mechanical measurement and ultrasound radio frequency (RF) signal analysis are proposed as new measures more closely related to the functional impairments. METHODS: Thirteen young healthy women volunteers had two applications per day on one arm of topical Clobetasol propionate 0.05% for 28 days, and they were followed for 28 days more. Skin modifications were studied by high-frequency ultrasound imaging, ultrasound RF signal analysis, optical coherence tomography and by the suction test. RESULTS: For all the techniques, a statistically significant change is observed with treatment. Large variations, around 30%, are observed for all techniques, but less for ultrasound imaging (10%). Dermis and epidermis thickness presented stable measurements on the nontreated zone. At the end of the study, measures returned to normal. The dynamic is mainly observed within the first 14 days of treatment and within the first 14 days after its cessation. CONCLUSION: Similar dynamics of skin modification during corticosteroid treatment was observed with very different techniques. Moreover, the potential of RF ultrasound analysis and mechanical skin measurement for characterizing skin structural and functional impairments has been evaluated.

Molecular characterization of inflammation and Staphylococcus aureus colonization of involved skin of atopic dermatitis patients. A non-invasive approach.

Atopic dermatitis (AD) is a multifactorial chronic inflammatory disease mainly stemming from a genetic predisposition that leads to hypersensitivity to environmental factors and a common involvement of Staphylococcus aureus (SA) colonization. The aim of this work was to propose a new non-invasive approach to enumerate the genes coding for the toxins of SA in atopic skin samples. In parallel, the study aimed to evaluate the change in AD through 3 markers of the inflammatory response: IL-8, IL-1RA/IL-1alpha and IL-18. These methods were tested on 31 patients with AD, and finally on a group of 19 subjects for whom clinical improvement had been reported after various treatments. The study revealed the presence of a large number of genes encoding toxins in atopic samples, indicating a high rate of SA colonization, and also an increase in the level of all cytokine markers in atopic skin compared to the skin of healthy subjects. Finally, we found a positive correlation between increases in the SCORAD (Scoring Atopic Dermatitis Index) value after treatment and the corresponding evolution of the SA density. These methods provide a means to clinically evaluate the course of AD, and may help in the development of potential treatments.

Topography and anisotropy of the skin surface with ageing.

BACKGROUND/PURPOSE: Most studies of how the relief of the skin surface changes on ageing are based solely on topography, and a few have taken into account anisotropy parameters. However, the calculation of these parameters is often carried out manually and as the techniques of data acquisition have progressed rapidly, a certain degree of obsolescence has been reached. It is for this reason that we have undertaken a similar study but with more advanced equipment. MATERIALS AND METHODS: The Dermatop system analyses the relief of Silflo negative prints of the skin surface. It is based on the projection of interference fringes and phase shift and provides surface parameters and not profiles. In addition, the Toposurf software enables image processing and the precise and automatic calculation of the topography parameters (roughness, developed surface area and peak-trough amplitude) and anisotropy (level of anisotropy and furrow density). These parameters were studied on the forearm and temple of 40 men and 40 women evenly distributed into two groups: the first including subjects aged 25-35 years and the second 50-65 years. RESULTS: Roughness of both sites increases with age, independent of sex, but to a lesser extent in women than in men. The developed surface area and the peak-trough amplitude increase significantly with age irrespective of the site and the sex. The level of anisotropy increases with age, in both men and women, on the forearm and the temple, the site more exposed to light being more affected. The density of the furrows decreases with age in both sexes and both sites but with a greater increase for the temple, which is more exposed to solar ageing. CONCLUSION: The study of these new parameters will allow objective evaluation of the action of topical dermatological and cosmetic treatment, and new techniques in plastic surgery (e.g. laser resurfacing), and will enable the accurate follow-up of certain pathologies.

Skin topography measurement by interference fringe projection: a technical validation.

BACKGROUND/AIMS: The quantitative analysis of skin topography is frequently used in cosmetology to evaluate the efficacy of hydrating or anti-wrinkle creams (micro-topography studies) or creams for slimming or to alleviate stretch marks (macro-topography studies). Numerous methods involving the three-dimensional (3-D) reconstruction of the topography from silicone replicas have been developed. Some of the main techniques applied include optical profilometry based on the reflection of oblique lighting or on transparency, and profilometry by laser focusing or triangulation. METHODS: We chose to test the Dermatop system developed by Eotech Co., which is based on interference fringe projection profilometry associated with the Toposurf surface processing software. Owing to the system's principle of operation, we first ran three experiments to evaluate the influence of ambient lighting on the 3-D reconstruction and the surface roughness parameters, the influence of the calibration device built into the acquisition system and the influence of calibration in terms of ambient lighting correction. We then evaluated the accuracy, the repeatability and the reproducibility of the measurements provided by the system from known metal topographic standards and skin replicas. RESULTS: It was seen that external lighting can cause variations in the calculation of parameters SPa, SPt and SPtm which can reach error levels of about 5% if the operator does not almost systematically calibrate the apparatus between each measurement. These three experiments enabled us to standardise the protocol for the acquisition of 3-D information, in order to minimise the lighting problems and yet respect the requirements for routine studies. The correlation coefficient between the theoretical values and the mean of experimental values was 0.9955 for parameter SPa and 0.9983 for parameter SPtm. Repeatability presented variations of under 4%, irrespective of the parameters, and reproducibility of under 6%. CONCLUSIONS: The technique provides very satisfactory results from the point of view of accuracy, repeatability and reproducibility. It is an excellent compromise between cost, accuracy and the time required.