Photodermatology Flashcards
What is the condition whereupon individuals experience an abnormal reaction to sunlight and come up in a red itchy rash upon exposure.
Polymorphic skin eruption
What is a porphyria?
A group of disorders of certain enzymes whereby they are unable to participate in the production of porphyrins and haem. They result in a metabolic accumulation and manifest with either neurological complications or skin problems.
What is photosensitive eczema/chronic actinic dermatitis?
Thickened, lichenified plaques on sun exposed skin and there may be a previous history of eczema
Who is most commonly affected by photosensitive eczema?
Adult males
How is a diagnosis of photosensitive eczema made?
Monochromator light testing
What condition causes the person to come up in wheals within minutes f exposure to sunlight and then clear in one to two hours?
Solar urticaria
What is the condition whereby there are sun induced papules and lichenified modules which occur in childhood and usually resolve by adolescence.
Actinic prurigo
How does porphyria cutanea tarda present?
Blistering and fragility
After you have identified that a skin reaction is due to a porphyria what must you do next?
Identify what the underlying cause of the attack is.
Give 4 possible underlying causes of porphyria cutanea tarda
Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis
What are porphyrins?
The main precursors of heme in humans
What is the main problem underlying problem in porphyria?
An accumulation of porphyrins, which are toxic to tissues in high concentrations.
What is the most common precipitant of porphyria cutanea tarda?
Alcohol
How is a diagnosis of porphyria cutanea tarda made?
Increased levels of urinary uroporphyrin
What is the treatment for Porphyria cutanea tarda?
To relieve the skin disease
Treat the underlying diseases to reduce risk of liver cirrhosis, hepatoma etc
What porphyria presents with irritation and burning pain upon exposure to sunlight (in childhood)? Infants will often cry/scream when out in the sun.
Erythropoietic porphyria
What investigations would you carry out if you suspected erythropoietic porphyria?
Fluresence of the peripheral red blood cells. Also by the increased photoporphyrin in RBC’s and stools.
What is congenital erythopoietic porphyria?
An extremely rare autosomal recessive trait where there is extreme sensitivity to sunlight and patients develop very disfiguring scars.
What may be the symptoms of an acute intermittent porphyria?
Long periods of latency then an attack whereby there is:
- Abdominal pain
- Urinary symptoms
- Peripheral neuropathy
- Neuropsychiatric symptoms
How do you manage an acute photosensitive episode?
Symptomatically
Venesection (reduces urinary porphyria)
Chloroquinine
How do you prevent a future photocutaneous attack?
Avoid sunlight
Zinc containing suncream
Protective clothing
Oral beta carotene
How do you manage EPP?
Genetic counselling
6 monthly LFTs and RBC porphyrins
Visible light photo protection measures
