Porphyria/Photodermatology Flashcards
How many Normal Fitzpatrick sun-reactive skin phototype categories are there?
SPT i to iv (sometimes there is v& vi added)
Type 1 photosensitivity?
Always burns doesn’t tan
Type 2 photosensitivity?
Usually burns but then tans
Type 3 photosensitivity?
Mostly tans
Whar are chromophores?
The chemicals that absorb radiation
What do all the skin porphyrias involve?
Porphyrins as chromophores
Porphyrins accumulate depending on?
How much water is present
Main groups of porphyrias?
- Phototoxic skin porphyrias
- Blistering and fragility skin porphyrias
- Acute attack porphyrias
- Severe congenital porphyrias
Example of phototoxic skin porphyrias?
erthrypoietic protoporphyria
More common skin porphyria features?
Blistering and fragility
Acute phototoxic
Porphyria cutanea tarda (PCT) is type?
1
Porphria cutanea tarda involves the liver how?
Liver doesn’t break down a metabolite
2 steps to diagnose PCT?
Diagnosis of PCT
Diagnosis of the causes of PCT
Typical presentation of PCT?
Blisters Fragility -Hyperpigmentation -Hypertrichosis (abnormal hair growth) -Solar urticaria -Morphaea
Milia are?
Small white firm bumps (like the one under Jamie’s eyes)
How do milia occur?
When keratin becomes trapped under the surface of the skin
Investigations for porphyrians?
Woods lamp
Possible underlying causes of PCT?
Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis
Aims of PCT treatment?
Relieve the skin disease
Treat underlying diseases to reduce the liver cirrhosis, hepatoma
Woods lamp results for PCT?
Urine glows purple, whereas a normal patient would glow blue
What is EPP?
Erythropoietic protopoprhyria
Which enzyme has reduced activity in erythropoietic protoporphyria causing a build up of porphyrin?
Ferrochelatase
Investigations for EPP?
Quantitative RBC porphyrins Flurocytes Transaminases [Hb] Red cell indices Biliary tract USS Phototesting
Inheritence of EPP?
Autosomal co-dominant