Porphyria and photodermatology Flashcards
What is photobiology?
The study of non ionising radiation on living system
What are the two types of photosensitivity?
- phototoxicity
- photoallergy
A 32 year old man reports that if exposed to one hour of midday summer sunlight he gets sunburn but then he tans.
What is his sun-reactive skin phenotype?
2
Which site involvement is a clue to cutaneous photosensitivity?
Retroarticular (behind the ear)
Describe treatment options of photosensitivity
- behavioural avoidance
- clothing
- sunscreen use
- hardening
- phototherapy
- PUVA
- chromophore removal
- inhibition of mediator / action release
- inhibition of inflammatory response
Name the main groups of porphyrias
- phototoxic skin porphyrias
- blistering and fragility skin porphyrias
- acute attack porphyrias
- severe congenital porphyrias
Name some common skin porphyria features
- blistering and fragility
- acute phototoxic
Describe the typical presentation of porphyria cutanea tarda (PCT)
- blisters
- fragility
- hyperpigmentation
- hypertrichosis
- solar urticaria
- morphoea
Describe the management of porphyria cutanea tarda (PCT)
- decide the underlying cause and treat (alcohol, viral hepatitis, oestrogens, haemochromatosis
- aims to relieve the skin disease
Name investigations of erythropoietic protoporphyria
- quantitative RBC porphyrins
- fluorocytes (patient, relatives)
- transaminases
- [Hb], red cell indices
- biliary tract USS
- phototesting
Describe the management of erythropoietic protoporphyria
- explain diagnosis (genetic counselling)
- 6 monthly LFTs and RBC porphyrins
- visible light photoprotection measures (particular need for caution if surgery needed)
Describe photoprotection measures
- behavioural (eg avoid middle of day sunlight)
- clothing (importance of weave, colour, etc)
- environmental (eg shade trees, window films)
- topical sunscreen
