Photodermatology, An Issue of Dermatologic Clinics (eBook)

Henry Lim (Autor)

eBook Download: PDF | EPUB

2014 | 1. Auflage
217 Seiten
Elsevier Health Sciences (Verlag)
978-0-323-31180-9 (ISBN)

Infos

Dr Henry Lim, renown for expertise and research in photodermatology leads this issue of Dermatologic Clinics. Photodermatology in this issue addresses dermatoses brought on or accelerated by light as well as light forms for dermatology therapies. Photodermatology is used to diagnosis and treat many common conditions that bring patients to the dermatologist. Topics include: Introduction to photobiology; Evaluation of patients with photodermatologic conditions; Photoimmunology; Photoaging; Photocarcinogenesis; Polymorphous Light Eruption (PMLE); Actinic Prurigo; Hydroa vacciniforme and solar urticaria; Chronic actinic dermatitis; drug-induced photosensitivity; Cutaneous porphyrias; Photoaggravated dermatoses; Ultraviolet (UV) based therapy; Photodynamic therapy; Photoprotection. Dr Lim works with one his residents, So Yeon Paek, as his co-Editor on this issue.

Inhalt

Front Cover 1
Photodermatology 2
copyright 
3 
Contributors 4
Contents 8
Dermatologic Clinics 
12 
Preface 
14 
Introduction to Photobiology 16
Key points 16
Introduction 16
UVR 16
Solar Radiation 16
UVR 17
Light-Skin Interactions 17
Reflection, scattering, and absorption 17
Photochemical reactions 18
Basic principles of phototherapy 18
MED 19
Acute and Chronic Effects of UVR 20
UV Damage on a Molecular Level 20
DNA damage and repair 20
UVR-induced apoptosis 21
Role of lipids 21
Role of proteins 21
UV Damage on a Clinical Level 21
Sun exposure: acute and chronic effects 21
Sunburn and tanning 21
Vitamin D production 22
Photoaging 22
Carcinogenesis 24
Phototherapy 24
Phototesting with Artificial Light Sources 24
Arc lamps 25
Excimer 25
Fluorescent lamps 25
Light-emitting diodes 25
Lasers 25
Summary 26
References 26
Evaluation of Patients with Photodermatoses 28
Key points 28
Overview 28
History 29
Age of Onset 29
Seasonal Variation, Interval Before Onset, Duration of the Eruption 30
Family History 30
Systemic Abnormalities 30
Window Glass 30
Exposure to Photosensitizers 31
Epidemiology and prevalence 31
Pathophysiology 32
Clinical findings 32
Histology 33
Laboratory and Photobiology Tests 33
Blood tests 33
Phototesting 34
Photopatch testing 34
Treatment 35
Summary 35
References 35
Photoimmunology 38
Key points 38
Evidence of photoimmunologic effects of UV radiation in humans 38
Experimental evidence for the photoimmunologic effects of UV radiation 39
Mechanisms of UV-induced immune suppression 39
Regulatory T Cells 39
APCs 40
Initial Molecular Events 41
Cytokines and Other Soluble Mediators 42
TLRs and Innate Immunity 43
Photoimmunologic diseases 44
PMLE 44
Chronic Actinic Dermatitis 44
Cutaneous Lupus Erythematosus 44
Photoimmunologic effects of phototherapy 46
Summary 47
References 47
Photoaging 52
Key points 52
Introduction 52
History 52
Epidemiology 52
Pathogenesis 53
Clinical manifestations 54
Histology 54
Photobiologic evaluation 54
Treatment 55
Topical Retinoids 56
Cosmeceuticals 56
Chemical Peels 57
Neuromodulators 57
Soft Tissue Fillers 58
Light Sources 58
Summary 59
References 59
Photocarcinogenesis 62
Key points 62
Introduction 62
Biologic effects of UV 62
DNA Damage 63
Cell-Cycle Arrest 63
DNA Repair 64
Apoptosis 64
UV Effects on the Immune System 64
Nonmelanoma skin cancer 65
Epidemiology 65
Genetic Predisposition for NMSC 65
Sporadic Formation of NMSC 65
Occupational Exposure and NMSC 66
Indoor Tanning and NMSC 67
Melanoma 67
Genetic Predisposition to Melanoma 68
Sporadic Melanoma 69
Occupational Exposure and Melanoma 69
Indoor Tanning and Melanoma 69
UVR, vitamin D, and skin cancer 70
Summary 71
References 71
Polymorphous Light Eruption 76
Key points 76
Introduction 76
History 77
Epidemiology 77
General Epidemiology 77
Clinical manifestations 77
Quality of Life 78
Relation to Lupus Erythematosus 78
Histology and immunohistochemistry 79
Photobiologic evaluation 79
Waveband Aspects 79
Pathogenesis 80
Genetics 80
Potential Antigens in PMLE 80
General Immunologic Aspects 81
Cell Migration Patterns and Cytokines 82
Antimicrobial Peptides 84
Hormonal Factors 84
Vitamin D 85
Relation to Skin Carcinogenesis 85
Management 86
Prevention 86
Photohardening 86
Established Treatments 87
Experimental Approaches 87
Summary and perspectives 88
Acknowledgments 88
References 88
Actinic Prurigo 96
Key points 96
Introduction 96
History 96
Epidemiology 97
Pathogenesis 97
Association with HLA 98
Clinical manifestations 98
Histology 99
Laboratory findings 99
Photobiological evaluation 100
Treatment 100
Summary 102
References 102
Hydroa Vacciniforme and Solar Urticaria 106
Key points 106
Hydroa vacciniforme 106
History 106
Epidemiology 106
Pathogenesis 107
Clinical Manifestations 107
Mucocutaneous manifestations 107
Systemic manifestations 107
Histology 108
Differential Diagnosis 108
Laboratory Findings 108
Photobiological Evaluation 108
Management 108
Solar urticaria 108
History 108
Epidemiology 109
Clinical Manifestations 109
Associated Conditions 109
Differential Diagnosis 109
Pathogenesis and Classification 109
Action Spectrum 109
Inhibition Spectrum 110
Augmentation Spectrum 110
Photobiological Evaluation 110
Management 110
Medical therapy 110
Antihistamines 110
Cyclosporine 111
Methotrexate 111
Intravenous immunoglobulin 111
Omalizumab 111
a–Melanocyte stimulating hormone analogue 111
Procedural therapy 111
Phototherapy and photochemotherapy 111
Plasmapheresis 112
Prognosis 112
References 112
Chronic Actinic Dermatitis 116
Key points 116
History 116
Epidemiology 116
Pathogenesis 117
Diagnosis 117
Clinical Manifestations 117
Differential Diagnoses 117
Histology 117
Photobiological Evaluation 117
Laboratory Evaluation 118
Management 118
Prognosis 119
Summary 119
References 120
Drug-Induced Photosensitivity 124
Key points 124
Introduction 124
Epidemiology 125
Pathogenesis 125
Clinical manifestations 126
Laboratory findings 126
Photobiological evaluation 126
Management 127
References 128
The Cutaneous Porphyrias 130
Key points 130
Introduction 130
History 130
Pathogenesis of skin lesions 131
Diagnostic approach in cutaneous porphyria 132
General photoprotection 133
Porphyrias presenting with acute photosensitivity 133
Erythropoietic and X-Linked Dominant Protoporphyria 133
Epidemiology 133
Clinical features 134
Differential diagnosis 134
Laboratory findings 135
Management 135
Porphyrias presenting with fragile skin 135
Porphyria Cutanea Tarda 135
Epidemiology and pathogenesis 135
Clinical features 136
Differential diagnosis 136
Laboratory findings 136
Management 137
Complications 137
The Autosomal Dominant Acute Porphyrias 137
Epidemiology 137
Pathogenesis of acute attacks 137
Clinical manifestations 138
Laboratory findings 138
Management 138
Congenital Erythropoietic Porphyria 139
Epidemiology 139
Clinical manifestations 139
Laboratory findings 140
Differential diagnosis 140
Management 140
Complications 141
Rare porphyria variants 141
References 141
Photoaggravated Disorders 146
Key points 146
Introduction 146
Diseases usually exacerbated by UVR 147
Cutaneous Lupus Erythematosus 147
Introduction 147
History 147
Epidemiology 147
Pathogenesis 148
Clinical manifestations 148
Histology 149
Laboratory findings 149
Management 149
Darier Disease 150
Introduction 150
History 150
Epidemiology 150
Pathogenesis 150
Clinical manifestations 150
Histology 150
Management 150
Dermatomyositis 151
Introduction 151
History 151
Epidemiology 151
Pathogenesis 151
Clinical manifestations 151
Histology 151
Laboratory findings 152
Photobiologic evaluation 152
Management 152
Lichen Planus Actinicus 152
Introduction 152
Epidemiology 152
Pathogenesis 152
Clinical manifestations 152
Histology 152
Management 152
Pellagra 152
Introduction 152
Epidemiology 152
Pathogenesis 152
Clinical manifestations 153
Laboratory findings 153
Management 153
Rosacea 153
Introduction 153
History 153
Epidemiology 153
Pathogenesis 153
Clinical manifestations 153
Histology 153
Management 153
Smith-Lemli-Opitz Syndrome 154
Diseases sometimes exacerbated by UVR 154
Atopic Dermatitis 154
Pemphigus 154
Psoriasis 154
References 155
UV-Based Therapy 160
Key points 160
Introduction 160
History 160
UV-B 161
Mechanism of Action 161
Modes of Delivery 161
BB–UV-B phototherapy 161
NB–UV-B phototherapy 161
Targeted Phototherapy: Excimer Lasers and Lamps 162
Indications 162
Contraindications 162
Treatment Protocol 163
Expected Outcome 165
Side Effects 165
PUVA and UV-A1 165
Mechanism of Action 165
Modes of Delivery 166
PUVA 166
UV-A1 166
Indications 166
Contraindications 166
Expected Outcome 166
Treatment Protocol 167
Side Effects 167
Summary 169
References 169
Photodynamic Therapy 176
Key points 176
Introduction 176
Historical perspective 176
Mechanism of action 177
Sensitizer 177
Light source 177
Therapeutic applications and expected outcomes 178
Photorejuvenation 178
Acne Vulgaris 179
Verrucae 180
Actinic Keratosis 180
NMSC 181
Bowen Disease 181
BCC 182
Management of adverse events 182
Pain 182
Cold air 183
Injectable anesthetics 183
Interruption of treatment 183
Topical anesthetics 184
Phototoxicity 184
Infection 184
Immunosuppression 184
Scarring 184
Pigmentation 184
Risk of Carcinogenesis 185
Summary 185
References 185
Sunscreens 188
Key points 188
Introduction 188
Mechanism of action 189
Health benefits of using sunscreen 189
Prevention of AK and SCC 190
Reduction of Basal Cell Carcinoma 191
Prevention of Melanoma 192
Prevention of Skin Aging 192
Management of Photodermatoses 192
FDA regulation on sunscreen labeling and effectiveness testing 192
Controversies associated with sunscreens 195
Safety of Oxybenzone 195
Safety of Nanoparticles 195
Sunscreen-Induced Vitamin D Deficiency 196
Limitations of sunscreen use 196
Summary 196
References 196
Photoprotection 200
Key points 200
Introduction 200
Photoprotection by glass 200
Main Types of Glass 200
UV Transmission Through Residential Glass 201
UV Exposure in Automobiles 201
Automobile Glass 201
UV transmission through automobile glass 202
Window films 202
Photoprotection with sunglasses 203
UV Exposure and the Eye 203
Sunglasses Guidelines 203
Photoprotection by clothing 204
Methods for Assessing the UPF of Textiles 204
In vitro method 204
In vivo method 205
Influence of Fabric Parameters on UPF 206
Porosity, Weight, and Thickness 206
Type of Fabric 206
Color of Fabrics 206
Laundry 206
Moisture Content 206
Stretch 207
Fabric to Skin Distance 207
Fabric Processing 207
UV Absorbers 207
Summary 207
References 208
Index 210

Textauszug

Introduction to Photobiology

Elma D. Baron, MDa∗[e-mail] and Amanda K. Suggs, MDb,     aDepartment of Dermatology, University Hospitals Case Medical Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Lakeside 3500, Mailstop 5028, Cleveland, OH 44106-5028, USA; bDepartment of Dermatology, University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA

∗Corresponding author.

Photobiology is the study of the local and systemic effects of incident radiation on living organisms. Solar radiation is made up of ultraviolet, visible and infrared radiation. Ultraviolet radiation is made up of UV-C, UV-B, and UV-A. Sun exposure can lead to sunburn, tanning, vitamin D production, photoaging, and carcinogenesis. Phototherapy is the use of nonionizing radiation to treat cutaneous disease. Various types of artificial light sources are used for photo testing and phototherapy.

Keywords

Ultraviolet radiation

Ultraviolet light

Phototherapy

Photobiology

Sunburn

Melanogenesis

Vitamin D production

Photoaging

Key points

• Solar radiation is made up of ultraviolet, visible, and infrared radiation.

• Ultraviolet radiation is made up of UV-C, UV-B, and UV-A.

• Most ultraviolet radiation that reaches the earth is UV-A.

• Sun exposure has a wide range of biological effects, including sunburn, tanning, vitamin D production, photoaging, and carcinogenesis.

• Phototherapy uses properties of ultraviolet light that are useful in the treatment of certain dermatologic conditions.

Introduction

Photobiology deals with the local and systemic effects of incident radiation on living organisms. This introductory article on cutaneous photobiology focuses on the effects of ultraviolet (UV) radiation (UVR), both from its natural source (ie, the sun) and artificial sources (ie, those used in phototherapy), on skin function and diseases. Although visible light and infrared radiation also have effects on skin cells, there is more information on UVR.

Phototherapy is the use of nonionizing radiation to treat cutaneous disease. For more than a century, phototherapy has played a pivotal role in the treatment of dermatologic diseases. In 1903, Niels Finsen received the Nobel Prize in Medicine for using light to treat a cutaneous mycobacterial disease. In the middle of the 20th century, advancements in UV-B light therapy expanded treatment options for patients with psoriasis. In the 1970s, photochemotherapy (ie, using psoralen as a photosensitizer in combination with UV-A radiation [PUVA]) made its debut. PUVA became an established player in the treatment of skin diseases in the last quarter of the 20th century. More recent advances in the last few decades (ie, narrowband UV-B therapy, laser therapy, targeted phototherapy, photodynamic therapy [PDT], UV-A1) have also revolutionized photodermatology.1,2

UVR

Solar Radiation

The rays of the sun hit the earth in the form of UVR, visible, and infrared radiation. These 3 entities are components of the electromagnetic spectrum, which also includes radiowaves, microwaves, radiographs, and γ radiation (Fig. 1). Solar radiation is made up of approximately 50% visible light, 40% infrared, and 9% UVR.3 Visible radiation is that which is perceived by the human eye.4 Each color of visible light represents a different wavelength range (see Fig. 1). UVR is the area of the electromagnetic spectrum that is considered most biologically active and therefore of greatest impact on health and disease.

Fig. 1 Electromagnetic spectrum.

UVR

UVR spans the wavelengths 100 to 400 nm and is subdivided into UV-C, UV-B, and UV-A. There are subtle differences in the subdivisions described in the literature. In this article, the subdivision most commonly chosen in photobiology is used (ie, UV-C, 200–290 nm; UV-B, 290–320 nm; and UV-A, 320–400 nm).4 Other ranges referenced in the literature include: UV-C at 200 to 280 nm, UV-B at 280 to 320 nm, UV-A at 320 to 400 nm, UV-C at 200 to 280 nm, UV-B at 280 to 315 nm, and UV-A at 315 to 400 nm.5 The stratospheric ozone prevents wavelengths shorter than approximately 290 nm from hitting the earth. Most UV radiation that reaches the earth is UV-A. Only a small percentage (approximately 5%) of UV-B is present in terrestrial sunlight. UV-C is typically filtered by the ozone layer.6 The amount of solar energy at a specific wavelength that can affect the earth varies with season, region, altitude, pollution, and the path that the solar radiation traverses through the ozone.7 The amount of UV in sunlight also varies throughout the day. Being of a longer wavelength, UV-A is present consistently from sunrise to sunset, whereas UV-B peaks around noon. Approximately 50% of UV-A exposure occurs in the shade as a result of surface reflection and its penetration to cloud cover. Windows and automotive glass do not shield against UV-A but do shield against UV-B.8

For the purposes of phototherapy, UV-B has been further subdivided into broadband UV-B (290–320 nm) and narrrowband UV-B (311 nm–313 nm). UV-A radiation has been subdivided into UV-A1 (340–400 nm) and UV-A2 (320–340 nm), primarily because the biological effect of UV-A2 is closer to that of UV-B. The specific applications of these modalities are discussed in more detail in the article by Rkein and Ozog elsewhere in this issue.

Light-Skin Interactions

Light has both the properties of waves and particles known as photons. In cutaneous photobiology, it is important to understand what happens to photons when they encounter the skin surface. They can undergo reflection, scattering, or absorption. According to the Grothus-Draper law, light can have a biological effect only if it is absorbed. Once radiation is absorbed by molecules in the skin (termed chromophores), energy is transferred to produce heat or drive photochemical reactions. This process results in detectable responses at the cellular and molecular levels that could lead to a clinical outcome (Fig. 2).9,10

Fig. 2 Light-skin interaction pathway.

Reflection, scattering, and absorption

Reflection happens at the skin surface. Light reflected from the skin can be used for diagnostic purposes but does not have much of a therapeutic role. Scattering alters the direction of the light transmission through the skin. How deep a photon can go is influenced by how much it is scattered by structures in the skin. Most scattering takes place in the dermis as a result of the presence of collagen. Scattering of radiation is also wavelength dependent; shorter wavelengths scatter more, whereas longer wavelengths penetrate deeper.9,10

The depth of light penetration is critical for phototherapy. UV-B is generally absorbed in the epidermis and upper dermis, whereas UV-A (because of its longer wavelengths) penetrates well into the dermis (Fig. 3). Shorter wavelength visible light such as blue light can be used in PDT for epidermal growths (such as actinic keratoses). Red light, which is of a longer visible wavelength, can target deeper structures such as sebaceous glands and thicker lesions.11 Nonetheless, penetration depth is only 1 part of the equation. The light must also be of the appropriate wavelength to be absorbed by the target molecule or chromophore. Only on absorption can a photon exert a clinical effect.

Fig. 3 UV wavelength and depth of skin penetration.

Different wavelength(s) target different chromophores, which results in a variety of cutaneous effects.11 Chromophores can be cellular/molecular components, such as amino acids, nucleotides, lipids, and 7-dehydrocholesterol (a vitamin D precursor). They can also be porphyrins (exogenous or endogenous), tattoo pigments, or photosensitizing drugs (eg, psoralens).10 DNA directly absorbs UV-B and is therefore a chromophore targeted by UV-B phototherapy. In cosmetic laser treatments, endogenous chromophores targeted are mainly hemoglobin, melanin, and water.12 Exogenous substances (ie, aminolevulinic acid solution, which converts to protoporphyrin IX) may also be used to act as chromophores, depending on the phototherapeutic modality.

Absorption is wavelength dependent and is influenced by the physicochemical structure of the chromophore.4,10 Each chromophore has an absorption spectrum, which is the range of wavelengths that are absorbed by that molecule. For example, the absorption spectrum for melanin is 250 to 1200 nm.13 The...

Produkt-Details

• Erscheint lt. Verlag: 8.9.2014
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Dermatologie
• ISBN-10: 0-323-31180-6 / 0323311806
• ISBN-13: 978-0-323-31180-9 / 9780323311809