Photosensitive Skin Diseases Flashcards
What is sunburn?
Erythema and vasodilation of skin causes by excessive UV radiation 2-6 hours post-exposure
Sunburn symptoms
Erythematous
Tender
Hot to touch
Blistering
Severe = blistering, dehydration, infection, electrolyte imbalance, shock
Followed by desquamation and pigmentation
Describe polymorphic light eruption
Prickly heat
Itchy erythematous eruption
Spares habitually exposed areas (face, hands)
?autoimmune inflammatory response of skin to UV radiation
Polymorphic light eruption (PLE) treatment
Sun avoidance/sunblock
Severe = topical/oral steroids
Prophylactic UVB/PUVA
What does spf on sun cream refer to?
UVB protection
(Sun protection factor)
What do stars on sun cream refer to?
UVA protection
Describe chronic actinic dermatitis
Men >50 years
Itchy, erythematous, thickened xeroderma
Sun-exposed skin
Chronic actinic dermatitis treatment
Sun avoidance/sunblock
Emollients, topical steroids
What is solar urticaria?
Urticaria within minutes of UV light
Lasts several hours
Raised erythematous weals
What is actinic prurigo?
Photosensitivity causing very itchy papules on sun-exposed areas
Normally manifests children <10
More common in darker skin types
Often lips and face
Actinic prurigo treatment
Emollients
Topical steroids
Hydroxychloroquine
Desensitisation
What is Hydroa Vacciniforme?
Blisters over sun-exposed areas
Heal with scarring
30-120 mins after exposure
Burning sensation/itching
Resolves once teenager but left with scarring
What is xeroderma pigmentosum?
Rare autosomal recessive defect in DNA repair results in photosensitivity’, skin ageing, tendency to skin cancers
Can be associated with neurological or ocular disease
Xeroderma pigmentosum management
Sun avoidance/protection
Regular skin examinations
What causes cutaneous porphyrias?
Defective enzyme in haem synthesis (mainly in liver and bone marrow)
Porphyria Cutanea Tarda (PCT) presentation
Erythema
Blisters
Erosions
Hypertrichosis
In response to UV radiation or minor trauma
Often on hands, face, neck and chest
Porphyria Cutanea Tarda causes
Inherited (autosomal dominant or sporadic)
Alcohol
Oestrogen
Iron overload
Pesticides
Porphyria Cutanea Tarda investigation
Biopsy
Urinary porphyrins
Woods light (fluoresces coral pink)
Porphyria Cutanea Tarda treatment
Avoid alcohol, oestrogens, iron
Sunblock/avoidance
Venesection if necessary
Rarely hydroxychloroquine
Cutaneous lupus erythematosus presentation
Malar (butterfly) rash
Photosensitivity
Mouth ulcers
Urticaria
Hair thinning
Which drugs can induce lupus?
Hydralazine
Carbamazepine
Lithium
Phenytoin
Sulphonamides
Minocycline
What is a phototoxic reaction? (Drug induced photosensitivity)
Exaggerated sunburn reaction
Minutes/hours after exposure
Photopatch negative
What is a photo allergic reaction? (Drug induced photosensitivity)
Eczematous type reaction
May spread to non-exposed areas
Hyperpigmentation does not occur
Photo patch positive
What causes phytophoyodermatitis and what does it look like?
Organic psoralens found in lime, celery, carrot, hog weed etc
Rash appears after subsequent UV exposure
Irregular erythema and blistering
Which diseases can UV worsen?
Darier’s
HSV
Pellagra
Photoaggravated psoriasis
Which diseases can UV improve?
Atopic eczema
CTCL
Pityriasis lichenoides
Pityriasis rosea
Psoriasis
Pruritis of renal failure and liver disease
