porphyria and photo dermatology

Question 1

what are causes of cutaneous photosensitivity (normal and abnormal)?

Answer 1

idiopathic, immunological
photoallergy
phototoxicity incl. metabolic conditions

Question 2

what do all skin porphyrias involve?

Answer 2

porphyrins as chromophores (chemicals that absorb radiation)
manifests in skin mainly relate to where porphyrins mainly accumulate
where they accumulate depends on how water or fat soluble they are

Question 3

what are the different porphyrias?

Answer 3

phototoxic skin
blistering and fragility
acute attack
severe congenital

Question 4

what are some of the symptoms of porphyria cutanea tarda (PCT)?

Answer 4

rash worse after hot bath/shower
blistering/crusting lesions on backs of hands/sun exposed areas

Question 5

what enzyme is involved in PCT?

Answer 5

uroporphyrinogen decarboxylase

Question 6

what are some underlying causes of PCT?

Answer 6

alcohol
viral hep
oestrogens
haemochromatosis

Question 7

what enzyme is involved in erythropoietic protoporphyria?

Answer 7

ferrochelatase

Question 8

what is the management of EPP?

Answer 8

genetic counselling (autosomal dominant)
6 monthly LFTs and RBC porphyrins
visible light photoprotection

Question 9

what are some photoprotection measures?

Answer 9

behavioural - avoid middle of day sun
clothing
environmental - shade, window films
topical suncream