1. No category

PHOTOSENSITIVITY SKIN
DISORDERS / PHOTODERMATOSES
Irene Horkay
Department of Dermatology
PHOTODERMATOSES (PD-S)
Number of PD-s: ever-increasing
depletion of the ozone layer
photosensitizing compounds, drugs, plants
sunbathing/sunbeds
Provoking spectrum: UV spectrum (200-400 nm)
of sunlight or artificial light sources
AETIOPATHOGENESIS OF PD-S
UV light alone
UV light + endogenous/exogenous photosensitizers
Metabolic – hormonal – immunological processes
Cellular and molecular targets / chromophores
DNA, porphyrins, etc.
DIAGNOSIS OF PD-S
Typical history: sunlight exposure, familial occurrence
Clinical features: morphology, localization
Phototests
minimal erythema/urtica dose (MED/MUD)
provocation test (idiopathic PD)
photopatch test (photoallergic dermatitis)
Laboratory tests
porphyrin analysis: urine, RBC, serum
immunoserology (autoantibodies: PLE, LE)
histology and immunhistology of skin lesions (PLE, HV, LE)
chromosomal analysis, UDS, urine amino acid levels
(geno-PD)
CLASSIFICATION OF
PHOTODERMATOSES (PD-S)
Yashar, Lim
I/ Idiopathic photodermatoses (PD-s)
II/ Photosensitivity secondary to external agents
III/ Cutaneous porphyrias
IV/ Genophotodermatoses
V/ Photoaggravated disorders
I/ IDIOPATHIC PHOTODERMATOSES
1/ Polymorphic light eruption (PLE)
2/ Juvenile spring eruption of the ears
3/ Solar urticaria (SU)
4/ Hydroa vacciniforme (HV)
5/ Chronic actinic dermatitis (CAD)
PATHOMECHANISM OF IDIOPATHIC PD
Abnormal immune response to sunlight
UV-induced antigen in the skin (unidentified)
Impaired immunoregulatory mechanism
Delayed (PLE, HV) or immediate type (SU) hypersensitivity reaction
skin lesions
Genetic basis + environmental factors
1/ POLYMORPHIC LIGHT ERUPTION (PLE)
Most frequent idiopathic PD
Action spectrum
UVB (290-320 nm), UVA (320-400 nm) or both
CLINICAL FEATURES OF PLE
Pleomorphic lesions mostly on the exposed areas
Erythematous papules
Papulovesicles/eczematous
Large plaques
CLINICAL FEATURES OF PLE
Diagnosis/treatment
Provocation phototest
60 - 90% positivity
Immunoserology: negative
Therapy/prevention: regular use of topical sunscreens
prophylactic narrow-band UVB
phototherapy
2/ JUVENILE SPRING ERUPTION OF THE EARS
Onset in childhood
Papules and vesicles on the ears
Dominance of boys
Spontaneous healing during
adolescence
3/ SOLAR URTICARIA
Action spectrum: 280 - 600 nm
Clinical features: itching, immediate wheal
Diagnosis: MUD/ provocation test
Treatment: antihistaminics,
prophylactic phototherapy
4/ HYDROA VACCINIFORME Bazin
Extremely rare
Onset in childhood, spontaneous healing during puberty
Clinical picture:papules, vesicles, vacciniforme scar
Prophylaxis: sunscreens, beta-carotene
5/ CHRONIC ACTINIC DERMATITIS
History: photoallergic contact dermatitis (drugs,
chemicals)
Action spectrum: UVA, UVB or both
Onset: middle/old age, male predominance
Clinical features:
1/ Persistent light reaction:perennial chronic
eczema without light exposure and chemicals
2/ Actinic reticuloid: nodular eruptions beyond the
exposed areas
Diagnosis: photopatch test
Treatment: symptomatic, preseasonal phototherapy
II/ PHOTOSENSITIVITY SECONDARY
TO EXTERNAL AGENTS
1/ PHOTOTOXIC
DERMATITIS
Action spectrum: UVA
Provoking agents: psoralen containing plants
tars, dyes – occupational skin disorders
cosmetics
drugs (tetracyclins, diuretics, amiodaron)
Clinical features: erythema, edema, blisters
healing: long-lasting pigmentation
Therapy: symptomatic
anti-H or corticosteroid
loc.: antiinflamm. + steroid
2/ PHOTOALLERGIC CONTACT
DERMATITIS
Action spectrum: UVA
Provoking agents: fragrances, sunscreens,
topical medicaments (NSAID-s)
Clinical features: eczematous eruptions
Diagnosis: photopatch testing
„crescendo” type reaction
Treatment: symptomatic
to avoid chemicals, drugs, sunlight
III/ CUTANEOUS PORPHYRIA
most common inherited cause of photosensitivity
1/ Erythropoietic porphyria
erythropoietic protoporphyria (EPP)
congenital erythropoietic porphyria (CEP, Günther’s
disease)
2/ Hepatic porphyria
porphyria cutanea tarda (PCT)
hepatoerythropoietic porphyria (HEP)
variegate porphyria (VP)
Action spectrum: UVA
1/ CHARACTERISTICS OF ERYTHROPOIETIC PROTOPORPHYRIA (EPP)
Onset of photosensitivity: early infancy
Inheritance: mostly autosomal dominant
Family history: frequent
Enzymatic defect: ferrochelatase
100 < heterogeneous mutations in the gene
Biochemistry: elevated PP in RBC
lack of porphyrinuria
CHARACTERISTICS OF EPP
Acute symptoms: painful erythema,
burning, swelling, urtica or blisters
Chronic signs: scarring, waxy thickening,
“orange peel” nose
occasionally: fatal hepatic failure
Treatment: beta-carotene
prophylactic UVB phototherapy
CEP (Günther’s disease)
Very rare
Clinical features: mutilating scarring
severe extracutaneous symptoms
Biochemistry: elevated porphyrin levels (RBC, urine)
No case in Hungary
2/ CHARACTERISTICS OF PORPHYRIA
CUTANEA TARDA (PCT)
Enzymatic defect: uroporphyrinogen decarboxylase
homozygous form of PCT: hepatoerythropoietic
porphyria (HEP)
Biochemistry: increased excretion of UP and CP
elevated liver specific enzyme activities
serum iron and ferritin level
Family history: rare
Background: hepatopathy of various origin (alcohol,
HCV infection, estrogens, chemicals)
CHARACTERISTICS OF PCT
Clinical features: skin fragility, blisters 
erosions 
scars + milia
hypertrichosis
pigmentation
Treatment: abstinence from alcohol
combined therapy: phlebotomies +
low dose of chloroquine
IV/ GENOPHOTODERMATOSES
Genetic defect(s) in the DNA-repair processes
Xeroderma pigmentosum
pigmented spots, early malignancis 
fatal outcome
Other biochemical abnormalities
Cockayne syndr.
Smith-Lemli-Opitz syndrome
Early development of malignancies
Specific extracutaneous features
V/ PHOTOAGGRAVATED DISORDERS
not real PD-s with different pathogenesis
Lupus erythematosus (LE)
malar erythema
Pemphigus group, pemphigoid
Dermatomyositis
Erythema multiforme
Atopic dermatitiss
Psoriasis, etc.