Photodermatology Flashcards
Which type of UV light causes sunburn/damage?
UVB
What are the available options for phototherapy?
Narrow band UVB most commonly used
New developments with UVA
What is photo chemotherapy?
Psoralen (sensitises the skin) + UVA
–> PUVA
Used second line as increased risk of skin cancer compared to UVB
What is polymorphic light eruption?
Few hours of sunlight –> erythematous papules and vesicles on exposed sights
Very common in young women
What is the management of polymorphic light eruption?
Resolves in a few days
UVB desensitisation therapy may help
What is actinic prurigo and what are the risk factors?
Similar to PLE but in children < 10
Sore red eyes, lips and end of nose
Also appears on covered sights
Associated with:
- FHx
- American Indians
- HLA DR4
What is solar urticaria?
Rare, type 1 hypersensitivity
Immediate, persistent, severe photosensitivity
Often to UVA with comes through windows/clothing
How is solar urticaria managed?
Antihistamines + UV desensitisation
–> difficult to manage
What is Xeroderma Pigmentosum?
Rare AR genetic disorder
Rapid photo ageing of the skin + skin cancers
Usually die in teenage years
What are some causes of drug induced photosensitivity?
Psoralens e.g. lime, celery, cow parsley Antibiotics e.g. sulphonamide, tetracyclines, fluoroquinolone Diuretics e.g. thiazides, furosemide NSAIDs Quinine Amiodarona
What are porphyrias?
Group of disorders caused by the build up of porphyrin in the body which causes damage to the skin and nervous system
Give two examples of porphyrias?
Porphyria cutanea tarda (acquired) Erythropoetic protoporphyria (inherited)
What are the biochemical findings and causes of porphyria cutaneous tarda?
Abnormal LFTs + iron overload
Causes include Hep C, HIV, haemochromatosis, alcohol
What are the features of erythropoietic protoporphyria?
Baby screams when put in sunlight
Which investigations should be done when a photodermatoses is suspected?
–> monochromator phototesting (shows which wavebands sensitive to)
Others:
- provocation test
- MED (minimal erythemal dose) test
- patch and photo patch tests
- urinary/blood porphyrins
- lupus studies
- HLA status
- histology
