Contact dermatitis

Question 1

Define contact dermatitis

Answer 1

Inflammatory skin reaction in response to an external stimulus acting as either an allergen or an irritant

Question 2

Aetiology of contact dermatitis

2

Answer 2

2 main types that may co-exist:

ALLERGIC - delayed type IV hypersensitivity reaction, which occurs after sensitisation & subsequent re exposure to allergen

IRRITANT - inflammatory response that occurs after damage to skin, usually by chemicals

Question 3

Common allergens

4

Answer 3

cosmetics (e.g. fragrance)
metals
topical medications
textiles

Question 4

Common irritants

3

Answer 4

detergents & soaps
solvents
powders

Question 5

Epidemiology of contact dermatitis

prevalence, location

Answer 5

4-7% of all dermatology consultations

Hands most commonly affected

Question 6

Presenting symptoms & signs of contact dermatitis

9

Answer 6

Hands are most frequently affected 
Can occur in axillae, groin & feet due to clothing
Redness of skin
Vesicles & papules in affected area
Crusting & scaling of skin
Itching of affected area
Fissures
Hyperpigmentation
Pain or burning sensation

Question 7

Investigations for contact dermatitis

2

Answer 7

NO investigations necessary most of the time

Some may need patch testing