Salvador González

The latest on skin photoprotection

UV radiation is the main etiological agent of most types of skin cancer and a key factor responsible for photoaging. Photoprotection is thus critical to avoid these undesired effects. Sunscreens rank among the best photoprotective measures. Sunscreens are the main components of lotions and creams used to prevent UV-induced damage or to ameliorate its harmful effects. There are 3 types of sunscreens: physical photon blockers, antioxidants, and stimulators of repairing mechanisms. This review summarizes current topics in the development of sunscreens, with special emphasis on substances of natural origin bearing photoscreening, antioxidant, or repairing properties. The characterization of different parameters to evaluate the effects of sunscreens, such as the sunscreen protection factor, is discussed. Finally, the effect of public awareness and public health campaigns are also reviewed.

Allergic contact dermatitis: Correlation of in vivo confocal imaging to routine histology

BACKGROUND Allergic contact dermatitis (ACD) is a common and often challenging clinical problem. In vivo near-infrared confocal reflectance microscopy (CM) is a new vital microscopy technique. OBJECTIVE CM was used to evaluate acute ACD. METHODS Patch testing by means of Finn Chambers technique was performed in 5 subjects to induce an acute allergic skin reaction. Noninvasive CM images from normal and eczematous skin were sequentially recorded before and after removal of the Finn Chambers. RESULTS The epidermis and papillary dermis were clearly seen in high resolution. Retention of nuclei in stratum corneum, epidermal edema with microvesicle formation, and transepidermal migration of inflammatory cells were observed in vivo. Isolated dendritic cells were present in the ACD sites of 2 subjects, with morphology, size, and location consistent with Langerhans cells. Dermal vasodilation was observed as well. CONCLUSION CM is a useful tool to study ACD and may be able to track Langerhans cell activation.

Clinical applicability of in vivo reflectance confocal microscopy for the diagnosis of actinic keratoses.

BACKGROUND In vivo reflectance confocal microscopy (RCM) has been used for evaluation of the morphologic features of nonmelanoma skin cancer. The application of RCM for diagnosis of basal cell carcinoma has been reported; however, the evaluation of actinic keratoses (AKs) has only been the subject of preliminary studies. STUDY GOAL The goal of this study was to evaluate the applicability of RCM in the diagnosis of AK in correlation with routine histology. MATERIALS AND METHODS Forty-four Caucasians with a minimum of one AK participated in this study. Evaluation consisted of clinical examination, RCM, and routine histology, including a total of 46 AKs in the final analysis. Ten normal skin sites served as controls. RCM features of AK included parakeratosis, architectural disarray, and keratinocyte pleomorphism. Following blinded evaluations, sensitivity/specificity, kappa analysis, and Spearmans correlation were performed on all parameters. RESULTS Sensitivity/specificity values of RCM features ranged from 80% to 98.6%. The presence of architectural disarray and cellular pleomorphism appeared to be the best predictor of AK. CONCLUSION In summary, RCM may be a promising technology for the noninvasive detection of AK and as adjunct tool to clinical diagnosis and monitoring. However, the preliminary nature of this study warrants further investigations.

Noninvasive Imaging of Human Oral Mucosa in Vivo by Confocal Reflectance Microscopy

Objectives/Hypothesis: To study the microscopic anatomy of normal oral tissues in vivo using confocal reflectance microscopy (CRM). This novel and noninvasive imaging modality can define and characterize healthy oral mucosa and thus this work serves as the foundation for studying oral diseases in vivo.

Actinic keratoses: non‐invasive diagnosis for field cancerisation

Summary Background  Actinic keratoses (AKs) are among the most common cutaneous malignancies and have previously been classified as in situ squamous cell carcinoma (SCC) with reported progression rates of up to 20% over 10 years. Since current scientific evidence suggests the presence of multilocular preneoplastic changes in the areas surrounding the affected skin sites, the detection of subclinical AKs remain an ongoing and challenging effort in the clinical and diagnostic management of these lesions. In vivo reflectance confocal microscopy (RCM) has been used for evaluation of the morphological features of non‐melanoma skin cancer (NMSC) and RCM evaluation parameters for the diagnosis of AKs have been reported.

Inhibition of ultraviolet-induced formation of reactive oxygen species, lipid peroxidation, erythema and skin photosensitization by Polypodium leucotomos

González S, Pathak MA. Inhibition of ultraviolet‐induced formation of reactive oxygen species, lipid peroxidation, erythema and skin photosensitization by Polypodium leucotomos. Photodermatol Photoimmunol Photomed 1996: 12: 45–56.

Topical or oral administration with an extract of Polypodium leucotomos prevents acute sunburn and psoralen-induced phototoxic reactions as well as depletion of Langerhans cells in human skin

Sunburn, immune suppression, photoaging, and skin cancers result from uncontrolled overexposure of human skin to solar ultraviolet radiation (UVR). Preventive measures, including photoprotection, are helpful and can be achieved by topical sunscreening agents. Polypodium leucotomos (PL) has been used for the treatment of inflammatory diseases and has shown some in vitro and in vivo inmunomodulating properties. Its beneficial photoprotective effects in the treatment of vitiligo and its antioxidant properties encouraged us to evaluate in vivo the potentially useful photoprotective property of natural extract of PL after topical application or oral ingestion. Twenty‐one healthy volunteers [either untreated or treated with oral psoralens (8‐MOP or 5‐MOP)] were enrolled in this study and exposed to solar radiation for evaluation of the following clinical parameters: immediate pigment darkening (IPD), minimal erythema dose (MED), minimal melanogenic dose (MMD), and minimal phototoxic dose (MPD) before and after topical or oral administration of PL. Immunohistochemical assessment of CD la‐expressing epidermal cells were also performed. PL was found to be photoprotective after topical application as well as oral administration. PL increased UV dose required for IPD (P<0.01), MED (P<0.001) and MPD (P<0.001). After oral administration of PL, MED increased 2.8±0.59 times and MPD increased 2.75±0.5 and 6.8±1.3 times depending upon the type of psoralen used. Immunohistochemical study revealed photoprotection of Langherhans cells by oral as well as topical PL. The observed photoprotective activities of oral or topical PL reveal a new avenue in examining the potentially useful field of systemic photoprotection and suggests that PL can be used as adjunct treatment and can make photochemotherapy and phototherapy possibly safe and effective when the control of cutaneous phototoxicity to PUVA or UVB is a limiting factor in such phototherapies.

Concordance between in vivo reflectance confocal microscopy and histology in the evaluation of plaque psoriasis.

Background   Psoriasis is a common skin inflammatory disease that affects 2% of the general population. Plaque psoriasis (PP) is its most common variant. In vivo reflectance confocal microscopy (RCM) is a non‐invasive, reproducible imaging technique that has proven to give useful information for morphometric evaluation of several inflammatory skin conditions, such as acute contact dermatitis and discoid lupus.

Treatment of vitiligo vulgaris with narrow‐band UVB and oral Polypodium leucotomos extract: a randomized double‐blind placebo‐controlled study

Background  The first choice treatment for vitiligo vulgaris is narrow‐band UVB (NB‐UVB), but no satisfactory treatment exists.

Drug photosensitivity, idiopathic photodermatoses, and sunscreens

Photosensitization may be defined as a process in which a reaction to normally innocuous radiation is induced by the introduction of a specific radiation-absorbing substance (the photosensitizer) that causes another component (the substrate) to be changed by the radiation. This review focuses on photosensitization produced by exogenous chemicals. Idiopathic photodermatoses, including polymorphous light eruption and its variants, solar urticaria and chronic actinic dermatitis, are also discussed. Clinical recognition patterns of the photodermatoses are stressed as well as several diagnostic procedures available for confirmation of the condition. Finally, descriptions, therapeutic uses, and adverse reactions of sunscreens are provided.