Photodermatology

Question 1

What is the condition whereupon individuals experience an abnormal reaction to sunlight and come up in a red itchy rash upon exposure.

Answer 1

Polymorphic skin eruption

Question 2

What is a porphyria?

Answer 2

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.

Question 3

What is photosensitive eczema/chronic actinic dermatitis?

Answer 3

Thickened, lichenified plaques on sun exposed skin and there may be a previous history of eczema

Question 4

Who is most commonly affected by photosensitive eczema?

Answer 4

Adult males

Question 5

How is a diagnosis of photosensitive eczema made?

Answer 5

Monochromator light testing

Question 6

What condition causes the person to come up in wheals within minutes f exposure to sunlight and then clear in one to two hours?

Answer 6

Solar urticaria

Question 7

What is the condition whereby there are sun induced papules and lichenified modules which occur in childhood and usually resolve by adolescence.

Answer 7

Actinic prurigo

Question 8

How does porphyria cutanea tarda present?

Answer 8

Blistering and fragility

Question 9

After you have identified that a skin reaction is due to a porphyria what must you do next?

Answer 9

Identify what the underlying cause of the attack is.

Question 10

Give 4 possible underlying causes of porphyria cutanea tarda

Answer 10

Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis

Question 11

What are porphyrins?

Answer 11

The main precursors of heme in humans

Question 12

What is the main problem underlying problem in porphyria?

Answer 12

An accumulation of porphyrins, which are toxic to tissues in high concentrations.

Question 13

What is the most common precipitant of porphyria cutanea tarda?

Answer 13

Alcohol

Question 14

How is a diagnosis of porphyria cutanea tarda made?

Answer 14

Increased levels of urinary uroporphyrin

Question 15

What is the treatment for Porphyria cutanea tarda?

Answer 15

To relieve the skin disease

Treat the underlying diseases to reduce risk of liver cirrhosis, hepatoma etc

Question 16

What porphyria presents with irritation and burning pain upon exposure to sunlight (in childhood)? Infants will often cry/scream when out in the sun.

Answer 16

Erythropoietic porphyria

Question 17

What investigations would you carry out if you suspected erythropoietic porphyria?

Answer 17

Fluresence of the peripheral red blood cells. Also by the increased photoporphyrin in RBC’s and stools.

Question 18

What is congenital erythopoietic porphyria?

Answer 18

An extremely rare autosomal recessive trait where there is extreme sensitivity to sunlight and patients develop very disfiguring scars.

Question 19

What may be the symptoms of an acute intermittent porphyria?

Answer 19

Long periods of latency then an attack whereby there is:

• Abdominal pain
• Urinary symptoms
• Peripheral neuropathy
• Neuropsychiatric symptoms

Question 20

How do you manage an acute photosensitive episode?

Answer 20

Symptomatically
Venesection (reduces urinary porphyria)
Chloroquinine

Question 21

How do you prevent a future photocutaneous attack?

Answer 21

Avoid sunlight
Zinc containing suncream
Protective clothing
Oral beta carotene

Question 22

How do you manage EPP?

Answer 22

Genetic counselling
6 monthly LFTs and RBC porphyrins
Visible light photo protection measures