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1.
Epileptic Disord ; 26(3): 293-301, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38497935

ABSTRACT

OBJECTIVE: Photosensitivity is known to occur predominantly in children and adolescents and with a clear female predominance. Little is known on the prevalence of photosensitivity in older patients (50+) and its phenotypical appearance. METHODS: A retrospective observational study was performed investigating the prevalence of a photoparoxysmal EEG response (PPR) on at least one EEG during the period 2015-2021. Data were gathered from patients aged 50 years and older by retrieving clinical and EEG characteristics from existing medical records. Data on photosensitivity-related symptoms in daily life were gathered with telephone interviewing. RESULTS: In 248 patients a PPR had been elicited, of whom 16 patients (6.5%) were 50 years or older. In older patients, photosensitivity was a persistent feature of childhood-onset epilepsy (n = 8), of adult-onset epilepsy (n = 7), or an incidental finding (n = 1). In the 50+ group, 56% of photosensitive patients was female, whereas 72% in the total PPR-group. In six of 16 older patients, eye closure sensitivity was observed; two of these patients reported self-induction. Symptoms of photosensitivity in daily life were present in eight out of nine patients who consented in a telephone interview. For seven of these patients, wearing sunglasses was helpful. SIGNIFICANCE: Female preponderance for photosensitivity was not found in epilepsy patients of 50 years and older. In 44% of the older photosensitive patients in this series, the PPR was a feature of adult-onset epilepsy. Symptoms of photosensitivity in daily life in older patients with epilepsy seem comparable to those in younger patients, and thus worthwhile to diagnose and treat them equally.


Subject(s)
Electroencephalography , Humans , Female , Male , Middle Aged , Retrospective Studies , Aged , Photosensitivity Disorders/epidemiology , Photosensitivity Disorders/physiopathology , Photosensitivity Disorders/etiology , Aged, 80 and over , Epilepsy, Reflex/physiopathology , Epilepsy, Reflex/epidemiology , Epilepsy/epidemiology , Epilepsy/physiopathology
2.
Clin Neurophysiol ; 132(2): 365-371, 2021 02.
Article in English | MEDLINE | ID: mdl-33450559

ABSTRACT

OBJECTIVE: To characterize photoparoxysmal EEG response (PPR) using a standardized protocol of intermittent photic stimulation (IPS) and standardized definitions for PPR, classified into six types. METHODS: Using the SCORE system (Standardized Computer-Based Organized Reporting of EEG) we prospectively built a large database of standardized EEG annotations. In this study, we extracted the features related to PPR from the structured dataset consisting of 10,671 EEG recordings with IPS, from 7,188 patients. RESULTS: The standardized IPS protocol elicited PPR in 375 recordings (3.5%), in 288 patients (4%), with a preponderance among young (11-20 years) and female patients (67%). PPR was persistent in patients with multiple recordings. The most frequent type of PPR was activation of preexisting epileptogenic area (58%), followed by generalized-PPR limited to the stimulus train (22%). We could not find any recording with self-sustained posterior response. Seizures were elicited in 27% of patients with PPR, most often myoclonic seizures and absences, in patients with self-sustained generalized PPR. CONCLUSIONS: The most common type of PPR was accentuation of preexisting epileptogenic area. Self-sustained posterior response could not be documented. Self-sustained generalized-PPR had the highest association with seizures. SIGNIFICANCE: Using standardized stimulation protocol and definitions for PPR types, IPS provides high diagnostic yield.


Subject(s)
Electroencephalography/statistics & numerical data , Epilepsies, Myoclonic/physiopathology , Photosensitivity Disorders/physiopathology , Adolescent , Adult , Aged , Child , Child, Preschool , Databases, Factual , Electroencephalography/methods , Epilepsies, Myoclonic/classification , Epilepsies, Myoclonic/epidemiology , Female , Humans , Infant , Male , Middle Aged , Photic Stimulation , Photosensitivity Disorders/classification , Photosensitivity Disorders/epidemiology
3.
Epilepsia ; 61(9): e124-e128, 2020 09.
Article in English | MEDLINE | ID: mdl-32949474

ABSTRACT

Our goal was to assess the interrater agreement (IRA) of photoparoxysmal response (PPR) using the classification proposed by a task force of the International League Against Epilepsy (ILAE), and a simplified classification system proposed by our group. In addition, we evaluated IRA of epileptiform discharges (EDs) and the diagnostic significance of the electroencephalographic (EEG) abnormalities. We used EEG recordings from the European Reference Network (EpiCARE) and Standardized Computer-based Organized Reporting of EEG (SCORE). Six raters independently scored EEG recordings from 30 patients. We calculated the agreement coefficient (AC) for each feature. IRA of PPR using the classification proposed by the ILAE task force was only fair (AC = 0.38). This improved to a moderate agreement by using the simplified classification (AC = 0.56; P = .004). IRA of EDs was almost perfect (AC = 0.98), and IRA of scoring the diagnostic significance was moderate (AC = 0.51). Our results suggest that the simplified classification of the PPR is suitable for implementation in clinical practice.


Subject(s)
Brain/physiopathology , Electroencephalography , Epilepsy/classification , Photosensitivity Disorders/classification , Adolescent , Adult , Child , Child, Preschool , Epilepsies, Myoclonic/physiopathology , Epilepsy/physiopathology , Epilepsy, Absence/physiopathology , Female , Humans , Infant , Lafora Disease/physiopathology , Male , Middle Aged , Mitochondrial Encephalomyopathies/physiopathology , Myoclonic Epilepsy, Juvenile/physiopathology , Neurofibromatosis 1/physiopathology , Neuronal Ceroid-Lipofuscinoses/physiopathology , Observer Variation , Photic Stimulation , Photosensitivity Disorders/physiopathology , Reproducibility of Results , Rett Syndrome/physiopathology , Young Adult
4.
Epilepsy Res ; 165: 106377, 2020 09.
Article in English | MEDLINE | ID: mdl-32505867

ABSTRACT

The assessment of the effect of photic stimulation is an integral component of an EEG exam and is especially important in patients referred for ascertained or suspected photosensitivity with or without a diagnosis of epilepsy. A positive test result relies on eliciting a specific abnormality defined as the "photoparoxysmal response". Reliability of this assessment is strongly influenced by technical and procedural variables, a critical one represented by the physical properties of the stimulators used. Established clinical norms are based on data acquired with the "gold-standard" Grass PS stimulators. These are no longer commercially available and have been replaced by stimulators using light emitting diode (LED) technology. To our knowledge no comparative study on their efficacy has been conducted. To address this gap, we recruited 39 patients aged 5-54 years, referred to two specialized centers with confirmed of suspected diagnosis of photosensitive epilepsy or generalized epilepsy with photosensitivity in a prospective randomized single-blind cross-over study to compare two commercially available LED-bases stimulation systems (FSA 10® and Lifeline® stimulators) against the Grass PS 33 xenon lamp device. Our findings indicate that the LED systems tested are equivalent to the Grass stimulator both in identifying the PPR in affected individuals.


Subject(s)
Photic Stimulation , Photosensitivity Disorders/etiology , Poaceae , Xenon , Adolescent , Adult , Child , Child, Preschool , Epilepsy, Generalized/genetics , Epilepsy, Reflex/etiology , Female , Humans , Male , Middle Aged , Photic Stimulation/methods , Photosensitivity Disorders/physiopathology , Single-Blind Method , Young Adult
5.
Epilepsy Behav ; 107: 107046, 2020 06.
Article in English | MEDLINE | ID: mdl-32304987

ABSTRACT

AIM: In clinical practice, there is a prevailing notion that photosensitivity mostly occurs in children with epilepsy (CWE) with idiopathic generalized epilepsy. We investigated the distribution of epilepsy types and etiology in photosensitive children and the associations with specific clinical and electroencephalogram (EEG) variables. METHODS: In this retrospective cohort study, clinical data were acquired from all children that showed photosensitivity during systematic intermittent photic stimulation (IPS), over a 10-year interval at a tertiary level Children's Hospital, Winnipeg. Patient demographics, EEG findings, and clinical data and symptoms during IPS were abstracted. Classification of diagnoses using the International League Against Epilepsy (ILAE) 2017 guidelines was done by an expert panel. RESULTS: Seventy-eight photosensitive children were identified. Forty (51.3%) had generalized epilepsy (idiopathic: 27, structural: 2, other: 11) compared with 19 (24.4%) focal (idiopathic: 1, structural: 2, other: 16), 8 (10.3%) combined focal and generalized (structural: 4, other: 4), and 11 (14.1%) unknown epilepsy (other: 11); (χ2 (3) = 32.1, p = .000). Self-sustaining or outlasting photoparoxysmal responses (PPRs) occurred in association with all epilepsy types; however, the EEGs of focal CWE without treatment comprised almost solely of PPRs which outlasted the stimulus (8/10), in contrast to only 8/17 of focal CWE with treatment and to 13/26 of generalized epilepsy without treatment. Most frequency intervals in individual patients were less under treatment: a decrease in standardized photosensitivity range (SPR) was seen in 5 CWE, an increase in 2, and no change in 1 during treatment. Both CWE with focal and generalized epilepsy showed abnormal activity on EEG during hyperventilation (40% vs 65.7%). Thirteen out of 14 CWE with clinical signs during IPS had independent spontaneous epileptiform discharges (SEDs) in the EEG recording. CONCLUSION: Photosensitivity occurs in all types of epilepsy rather than in idiopathic generalized epilepsy alone. Surprisingly, there is a tendency for focal epilepsy to be associated with self-sustaining PPRs, especially when no treatment is used. Treatment tends to make the PPR more self-limiting and decrease the SPR. There is a tendency that clinical signs during IPS occur in EEGs in individuals with SEDs.


Subject(s)
Electroencephalography/methods , Epilepsies, Myoclonic/diagnosis , Epilepsies, Myoclonic/physiopathology , Epilepsy, Generalized/diagnosis , Epilepsy, Generalized/physiopathology , Photic Stimulation/adverse effects , Photosensitivity Disorders/diagnosis , Photosensitivity Disorders/physiopathology , Adolescent , Child , Child, Preschool , Cohort Studies , Epilepsies, Myoclonic/epidemiology , Epilepsy, Generalized/epidemiology , Female , Humans , Infant , Male , Photosensitivity Disorders/epidemiology , Retrospective Studies
6.
Photodermatol Photoimmunol Photomed ; 36(3): 200-207, 2020 May.
Article in English | MEDLINE | ID: mdl-32027041

ABSTRACT

BACKGROUND: Phototesting is part of the standard procedure for the evaluation of patients with photosensitivity disorders. The response of patients to targeted UVB or UVA radiation helps to find out more about the nature of photodermatosis. Nevertheless, there are no default values of the minimal erythema dose (MED). METHODS: This study evaluated data of 203 patients (131 female, 72 male, mean age 52 years) who were referred for phototesting to the University Hospital Zurich between 2012 and 2017. We retrospectively analyzed the demographic data, medical history, skin phototype, reaction to UVB and UVA radiation, and, if present, the diagnosis of photodermatosis. In patients who did not develop erythema at the highest tested UV doses, the next logical increment was taken for analysis. In case of UVA, the two periphery doses could not be evaluated due to technical issues, so the closest reliable UVA doses were used. RESULTS: The MED-UVB correlated with the skin type and increased with a higher phototype. No such correlation could be seen for MED-UVA. However, the MED-UVA was significantly reduced in patients with photodermatosis without significant differences between the subgroups of photodermatosis. More than half of the patients did not show a reduced MED despite a diagnosed photodermatosis. CONCLUSION: We showed, how different skin types with and without photodermatosis react to UV radiation. Based on the results, we suggested threshold doses that can be chosen for phototesting, presented which doses can be considered pathologic and showed the probability of a pathologic MED in correlation with a diagnosed photodermatosis.


Subject(s)
Erythema/etiology , Photosensitivity Disorders/physiopathology , Skin Pigmentation , Ultraviolet Rays/adverse effects , Adolescent , Adult , Aged , Aged, 80 and over , Child , Female , Humans , Male , Middle Aged , Photosensitivity Disorders/diagnosis , Reference Values , Retrospective Studies , Young Adult
7.
Dermatology ; 235(5): 400-406, 2019.
Article in English | MEDLINE | ID: mdl-31288228

ABSTRACT

BACKGROUND: The Fitzpatrick skin phototype scale (FSPTS) is a widely used instrument to assess skin type. METHODS: A cross-sectional survey collected responses from 254 subjects from Quito regarding self-reported FSPTS, gender, age, education, and tobacco and alcohol consumption. Univariate and multivariate logistic regression analyses were performed to determine if ethnicity, hair color, and eye color significantly predict FSPTS. In addition, we studied the correlation between FSPTS and the SCINEXA scale with Pearson's correlation coefficient. RESULTS: Ethnicity, eye color, and hair color are significant independent predictors of FSPTS (p < 0.0001). CONCLUSIONS: Patient self-reported race and pigmentary phenotypes are inaccurate predictors of sun sensitivity as defined by Fitzpatrick skin phototype. Our study does not fully represent the population of the country. There are limitations to using patient-reported race and appearance in predicting individual sunburn risk.


Subject(s)
Photosensitivity Disorders/classification , Photosensitivity Disorders/epidemiology , Skin Pigmentation , Adult , Aged , Aged, 80 and over , Cross-Sectional Studies , Ecuador/epidemiology , Female , Humans , Male , Middle Aged , Photosensitivity Disorders/diagnosis , Photosensitivity Disorders/physiopathology , Racial Groups , Risk Factors , Self Report , Skin Pigmentation/physiology , Sunburn/diagnosis , Sunburn/epidemiology , Sunburn/ethnology , Sunburn/physiopathology , Suntan/physiology
8.
Epileptic Disord ; 21(2): 177-184, 2019 Apr 01.
Article in English | MEDLINE | ID: mdl-30945640

ABSTRACT

To determine the integrity of colour perception, related to photic sensitivity, in patients with juvenile myoclonic epilepsy. Twenty-four patients with photoparoxysmal response, 27 patients without photoparoxysmal response, and 32 healthy individuals were investigated using the Farnsworth Munsell-100 Hue test to calculate error scores for total colour, blue/yellow, and red/green. No significant differences were observed regarding blue/yellow, red/green or total error score between juvenile myoclonic epilepsy patients with or without photoparoxysmal response. However, the data for all three scores were significantly higher in both patient groups compared to the healthy control group. In both patient groups, the blue/yellow error score was significantly higher than the red/green error score. We were unable to identify a relationship between photoparoxysmal response and colour vision in patients with juvenile myoclonic epilepsy. We believe that the underlying reason why juvenile myoclonic epilepsy patients had significantly higher blue/yellow, red/green, and total error score compared to the healthy control group may be due to GABA dysfunction, which is considered to play a role in the pathophysiology of this disease as well as the physiology of colour vision.


Subject(s)
Color Perception/physiology , Color Vision/physiology , Epilepsies, Myoclonic/physiopathology , Myoclonic Epilepsy, Juvenile/physiopathology , Photosensitivity Disorders/physiopathology , Adult , Female , Humans , Male , Young Adult
10.
Article in English | MEDLINE | ID: mdl-30901071

ABSTRACT

We describe the clinical and dermoscopic features and histopathological findings in a case of a 33-year-old female patient with an adult-onset photodermatosis. This eruption was not typical of well-established photodermatoses due to its apoptotic keratinocytes. To our knowledge, this is the first report of these combined clinical and pathologic features.


Subject(s)
Dermoscopy/methods , Lichenoid Eruptions/complications , Lichenoid Eruptions/pathology , Photosensitivity Disorders/pathology , Adult , Apoptosis/physiology , Arizona , Biopsy, Needle , Female , Humans , Immunohistochemistry , Keratinocytes/cytology , Keratinocytes/pathology , Lichenoid Eruptions/physiopathology , Photosensitivity Disorders/complications , Photosensitivity Disorders/physiopathology , Rare Diseases , Risk Assessment
11.
Postgrad Med ; 130(8): 673-686, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30296862

ABSTRACT

Porphyrias are disorders caused by defects in the biosynthetic pathway of heme. Their manifestations can be divided into three distinct syndromes, each attributable to the accumulation of three distinct classes of molecules. The acute neurovisceral syndrome is caused by the accumulation of the neurotoxic porphyrin precursors, delta aminolevulinic acid, and porphobilinogen; the syndrome of immediate painful photosensitivity is caused by the lipid-soluble protoporphyrin IX and, the syndrome of delayed blistering photosensitivity, caused by the water-soluble porphyrins, uroporphyrin, and coproporphyrin. Porphyrias can manifest with one, or with a combination, of these syndromes, depending on whether one or more types of molecules are being accumulated. Iron plays a significant role in some of these conditions, as evidenced by improvements in both clinical manifestations and laboratory parameters, following iron depletion in porphyria cutanea tarda, or iron administration in some cases of X-linked erythropoietic protoporphyria. While the pathophysiology of a specific type of porphyrias, the protoporphyrias, appears to favor the administration of zinc, results so far have been conflicting, necessitating further studies in order to assess its potential benefit. The pathways involved in each disease, as well as insights into their pathobiological processes are presented, with an emphasis on the development of photosensitivity reactions.


Subject(s)
Heme/metabolism , Photosensitivity Disorders/complications , Photosensitivity Disorders/physiopathology , Porphyrias/complications , Porphyrias/physiopathology , Porphyrins/metabolism , Iron/metabolism , Porphyria Cutanea Tarda/complications , Porphyria Cutanea Tarda/physiopathology , Porphyria, Erythropoietic/complications , Porphyria, Erythropoietic/physiopathology , Porphyrias/classification , Protoporphyrins/metabolism , Uroporphyrins/metabolism
12.
J Pak Med Assoc ; 68(6): 959-962, 2018 Jun.
Article in English | MEDLINE | ID: mdl-30323370

ABSTRACT

Mixed connective tissue disease (MCTD) is a rare disease and presents with varied overlapping symptoms of different connective tissue disorders. Many patients evolve into other connective tissue disorders with the passage of time. The case series included 20 patients with the diagnosis of MCTD, registered at the Rheumatology Clinic of Jinnah Postgraduate Medical Centre (JPMC), Karachi, from June 2010 to May 2015. Of these, 16 (80.0%) were female and 4 (20.0%) patients were male. The mean age was 30.5±8.9 years and the mean duration of illness was 4.5±2 years. Commonest presenting symptom was arthralgia in 17 (85%) patients. All the patients had positive ANA and anti-RNP antibodies. Over the disease course of 6 years, 2 (10%) patients evolved into Systemic lupus erythematosus (SLE); One each (5%) into Sjogren's syndrome, Scleroderma and Rheumatoid arthritis.


Subject(s)
Mixed Connective Tissue Disease/physiopathology , Adult , Arthralgia/etiology , Arthralgia/physiopathology , Autoantibodies/immunology , Erythema/etiology , Erythema/physiopathology , Facial Dermatoses/etiology , Facial Dermatoses/physiopathology , Female , Humans , Male , Middle Aged , Mixed Connective Tissue Disease/complications , Mixed Connective Tissue Disease/immunology , Oral Ulcer/etiology , Oral Ulcer/physiopathology , Pakistan , Photosensitivity Disorders/etiology , Photosensitivity Disorders/physiopathology , Raynaud Disease/etiology , Raynaud Disease/physiopathology , Ribonucleoprotein, U1 Small Nuclear/immunology , Synovitis/etiology , Synovitis/physiopathology , Young Adult
15.
J Med Genet ; 55(5): 329-343, 2018 05.
Article in English | MEDLINE | ID: mdl-29572252

ABSTRACT

BACKGROUND: Cockayne syndrome (CS) is a rare, autosomal recessive multisystem disorder characterised by prenatal or postnatal growth failure, progressive neurological dysfunction, ocular and skeletal abnormalities and premature ageing. About half of the patients with symptoms diagnostic for CS show cutaneous photosensitivity and an abnormal cellular response to UV light due to mutations in either the ERCC8/CSA or ERCC6/CSB gene. Studies performed thus far have failed to delineate clear genotype-phenotype relationships. We have carried out a four-centre clinical, molecular and cellular analysis of 124 patients with CS. METHODS AND RESULTS: We assigned 39 patients to the ERCC8/CSA and 85 to the ERCC6/CSB genes. Most of the genetic variants were truncations. The missense variants were distributed non-randomly with concentrations in relatively short regions of the respective proteins. Our analyses revealed several hotspots and founder mutations in ERCC6/CSB. Although no unequivocal genotype-phenotype relationships could be made, patients were more likely to have severe clinical features if the mutation was downstream of the PiggyBac insertion in intron 5 of ERCC6/CSB than if it was upstream. Also a higher proportion of severely affected patients was found with mutations in ERCC6/CSB than in ERCC8/CSA. CONCLUSION: By identifying >70 novel homozygous or compound heterozygous genetic variants in 124 patients with CS with different disease severity and ethnic backgrounds, we considerably broaden the CSA and CSB mutation spectrum responsible for CS. Besides providing information relevant for diagnosis of and genetic counselling for this devastating disorder, this study improves the definition of the puzzling genotype-phenotype relationships in patients with CS.


Subject(s)
Cockayne Syndrome/genetics , DNA Helicases/genetics , DNA Repair Enzymes/genetics , Photosensitivity Disorders/genetics , Poly-ADP-Ribose Binding Proteins/genetics , Transcription Factors/genetics , Adolescent , Adult , Child , Child, Preschool , Cockayne Syndrome/physiopathology , Cohort Studies , Female , Genetic Predisposition to Disease , Humans , Infant , Introns/genetics , Male , Mutation, Missense/genetics , Photosensitivity Disorders/physiopathology , Pregnancy , Ultraviolet Rays , Young Adult
16.
G Ital Dermatol Venereol ; 153(1): 111-114, 2018 Feb.
Article in English | MEDLINE | ID: mdl-27391311

ABSTRACT

Kindler syndrome is a rare autosomal recessive condition, characterized by multiple skin and mucosal abnormalities. Among the latter, esophageal involvement is an infrequent manifestation which may be completely asymptomatic or complicated by dysphagia. We report the case of two sisters presenting with cutaneous features and severe dysphagia. Endoscopic examination showed that the patients were affected by a rare condition named "esophageal web". Both patients showed significant improvement after balloon dilation. Clinicians should be aware of the potential complications of this disease, and the approach by balloon dilation should be considered as primary therapy in Kindler syndrome patients with esophageal web.


Subject(s)
Blister/diagnosis , Deglutition Disorders/etiology , Epidermolysis Bullosa/diagnosis , Periodontal Diseases/diagnosis , Photosensitivity Disorders/diagnosis , Adult , Blister/physiopathology , Endoscopy/methods , Epidermolysis Bullosa/physiopathology , Esophagus/pathology , Female , Humans , Iran , Periodontal Diseases/physiopathology , Photosensitivity Disorders/physiopathology , Siblings , Young Adult
17.
An. bras. dermatol ; 92(6): 774-778, Nov.-Dec. 2017. tab
Article in English | LILACS | ID: biblio-887115

ABSTRACT

Abstract: Background: Actinic prurigo (AP) is an idiopathic photodermatosis. Although its initial manifestations can appear in 6 to 8-year-old children, cases are diagnosed later, between the second and fourth decades of life, when the injuries are exacerbated. Objective: To identify risk factors associated with clinical manifestations of AP such as skin and mucosal lesions. Methods: Thirty patients with AP and 60 controls were included in the study, the dependent variable was the presence of skin or labial mucosal lesions, the independent variables were age, sex, solar exposure, living with pets or farm animals, exposure to wood smoke, smoking habit, years smoking, and hours spent per day and per week in contact with people who smoke. Results: Of the 30 diagnosed AP patients, 66.7% were female. Patients age ranged from 7 to 71 years and the mean age was 35.77 ± 14.55 years. We found significant differences with the age and cohabitation with farm animals. Those who lived with farm animals presented 14.31 times higher probability of developing AP (95% CI 3-78.06). Study limitations: This is a case-control study; therefore, a causal relationship cannot be proven, and these results cannot be generalized to every population. Conclusions: The identification of factors related to the development of AP increases our knowledge of its physiopathology. Moreover, identifying antigens that possibly trigger the allergic reaction will have preventive and therapeutic applications in populations at risk of AP.


Subject(s)
Humans , Animals , Male , Female , Child , Adolescent , Adult , Middle Aged , Aged , Young Adult , Photosensitivity Disorders/etiology , Skin Diseases, Genetic/etiology , Environmental Exposure/adverse effects , Photosensitivity Disorders/physiopathology , Skin Diseases, Genetic/physiopathology , Sunlight/adverse effects , Time Factors , Case-Control Studies , Logistic Models , Risk Factors , Age Factors , Statistics, Nonparametric , Hypersensitivity/etiology , Hypersensitivity/physiopathology , Animals, Domestic
18.
Adv Exp Med Biol ; 996: 111-122, 2017.
Article in English | MEDLINE | ID: mdl-29124695

ABSTRACT

Skin colour (specifically in relation to its melanin content and composition) has a marked influence on its interaction with ultraviolet light. Eumelanin has mainly photoprotective properties while pheomelanin has the ability to cause formation of reactive oxygen species. This difference is responsible for the difference in incidence and presentation of various idiopathic photodermatoses in dark skinned patients compared to those with lighter skin types. Certain conditions are peculiar to darker skins including pin point popular variant of polymorphous light eruption. These differences are discussed in this chapter while also highlighting the challenges faced in performing phototesting in patients with dark skin.


Subject(s)
Melanins/metabolism , Photosensitivity Disorders/etiology , Skin Pigmentation/radiation effects , Skin/radiation effects , Ultraviolet Rays/adverse effects , Adult , Child , Female , Humans , Male , Middle Aged , Oxidative Stress/radiation effects , Photosensitivity Disorders/diagnosis , Photosensitivity Disorders/metabolism , Photosensitivity Disorders/physiopathology , Predictive Value of Tests , Prognosis , Reactive Oxygen Species/metabolism , Risk Factors , Skin/metabolism , Skin/pathology
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