Photodermatology

Question 1

What is polymorphic light eruption?

Answer 1

Type IV cell mediated hypersensitivity where there is delayed onset papules and vesicles that appear. It is non scarring.

Question 2

What is actinic prurigo?

Answer 2

An intensely itchy skin condition caused by an abnormal reaction to sunlight (photosensitivity). It presents with small, intensely itchy papules (prurigo) on sun-exposed sites.

This happens in childhood and is more common in females. It resolves by adult.

Question 3

What is solar urticaria?

Answer 3

A rare persistent disease where you get an immediate onset and often severe photsensitivity to UVA and visible wavelenths.
It is a type 1 hypersensitivitvy

Question 4

How do you treat solar urticaria?

Answer 4

Antihistamines

Desensitisation

Question 5

What is xeroderma pigmentosum?

Answer 5

A rare autosomal recessive disease where there is a filure of DNA excisionr epair that causes rapid photoageing of the skin, skin cancer and death in teenage years

Question 6

What drugs can cause photosensitivity?

Answer 6

Psoralens 
Antibiotics (tetracyclines, fluoroquinolones) 
Diuretics 
NSAIDS 
Quinine 
Amioderone

Question 7

What is porphyria cutanea tarda?

Answer 7

Low levels of uroporphyrinigen decarboxylase deficiency causes a build u or uroporphyrinogen.

Presents as blistering lesions on sun exposed areas of the skin. It is a type 4 hyepersensitivity reaction.

Question 8

How do you make a diagnosis of porphyria cutanea tarda?

Answer 8

Uroporphyrinogen in the urine

Question 9

What can cause porphyria cutanea tarda?

Answer 9

Excess alsocol

Hepatitis C

Question 10

What is erythropoietic protoporphyria

Answer 10

A porphyria that presents in childhood and leads to acute photosensitivty of the skin. A few minutes of sun exposure causes itching, swelling and pain.