Porphyrias Flashcards
What is meant by cutaneous photosensitivity?
Abnormal skin reaction to UV, and sometimes visible, light
What is porphyria?
Hereditary disease where there is build up of porphyrins, caused by reduced enzyme activity in the haem pathway
These react with light to produce skin reactions
Name the 3 most common porphyrias
Porphoryia cutanea tarda
Erythropoietic protoporphyria
Variegate porphyria
How does porphyria cutanea tarda arise?
Reduced activity of uroporphyrinogen decarboxylase causes build up of uroporphyrins that react with light (not UV)
List symptoms of porphyria cutanea tarda
Blistering
Skin fragility
Hyperpigmentation
Hypertrichosis
List 4 causes of porphyria cutanea tarda
Alcohol
Viral hepatitis
High oestrogen
Haemachromatosis
How does erythropoietic protoporphyria arise?
Reduced activity of ferrochelatase causes build up of protoporphyrins
List symptoms of erythropoietic protoporphyria
Swelling/burning
Itching
Pain
How does acute intermittent porphyria arise?
Reduced activity of PBG deaminase causes build up of uroporphyrins (Doesn’t usually effect the skin)
Investigations for PCT?
Woods lamp
Measure the amount of porphyria persecutors/porphyrins in the blood
What is the management for PCT
Sun avoidence (e.g. window film for car or home)
Desensitisation to harden skin
Topical steroids if rash
What is the management for erythropoietic protoporphyria?
Monitor LFTs/RBC and stay away from visible light
Porphyria cutanea tarda can be genetic or sporadic (acquired). True/false?
True
